From 952852081db408259d5a546927f08e40d94701eb Mon Sep 17 00:00:00 2001
From: Philip Withnall <pwithnall@gnome.org>
Date: Tue, 28 Nov 2023 12:58:20 +0000
Subject: [PATCH 01/17] gdbusmessage: Cache the arg0 value
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Technically we can’t rely on it being kept alive by the `message->body`
pointer, unless we can guarantee that the `GVariant` is always
serialised. That’s not necessarily the case, so keep a separate ref on
the arg0 value at all times.

This avoids a potential use-after-free.

Spotted by Thomas Haller in
https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3720#note_1924707.

[This is a prerequisite for having tests pass after fixing the
vulnerability described in glib#3268, because after fixing that
vulnerability, the use-after-free genuinely does happen during
regression testing. -smcv]

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: #3183, #3268
(cherry picked from commit 10e9a917be7fb92b6b27837ef7a7f1d0be6095d5)
---
 gio/gdbusmessage.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/gio/gdbusmessage.c b/gio/gdbusmessage.c
index adddb31544..6c4a5bfbee 100644
--- a/gio/gdbusmessage.c
+++ b/gio/gdbusmessage.c
@@ -508,6 +508,7 @@ struct _GDBusMessage
   guint32 serial;
   GHashTable *headers;
   GVariant *body;
+  GVariant *arg0_cache;  /* (nullable) (owned) */
 #ifdef G_OS_UNIX
   GUnixFDList *fd_list;
 #endif
@@ -530,6 +531,7 @@ g_dbus_message_finalize (GObject *object)
     g_hash_table_unref (message->headers);
   if (message->body != NULL)
     g_variant_unref (message->body);
+  g_clear_pointer (&message->arg0_cache, g_variant_unref);
 #ifdef G_OS_UNIX
   if (message->fd_list != NULL)
     g_object_unref (message->fd_list);
@@ -1168,6 +1170,7 @@ g_dbus_message_set_body (GDBusMessage  *message,
   if (body == NULL)
     {
       message->body = NULL;
+      message->arg0_cache = NULL;
       g_dbus_message_set_signature (message, NULL);
     }
   else
@@ -1178,6 +1181,12 @@ g_dbus_message_set_body (GDBusMessage  *message,
 
       message->body = g_variant_ref_sink (body);
 
+      if (g_variant_is_of_type (message->body, G_VARIANT_TYPE_TUPLE) &&
+          g_variant_n_children (message->body) > 0)
+        message->arg0_cache = g_variant_get_child_value (message->body, 0);
+      else
+        message->arg0_cache = NULL;
+
       type_string = g_variant_get_type_string (body);
       type_string_len = strlen (type_string);
       g_assert (type_string_len >= 2);
@@ -2362,6 +2371,14 @@ g_dbus_message_new_from_blob (guchar                *blob,
                                                  2,
                                                  &local_error);
           g_variant_type_free (variant_type);
+
+          if (message->body != NULL &&
+              g_variant_is_of_type (message->body, G_VARIANT_TYPE_TUPLE) &&
+              g_variant_n_children (message->body) > 0)
+            message->arg0_cache = g_variant_get_child_value (message->body, 0);
+          else
+            message->arg0_cache = NULL;
+
           if (message->body == NULL)
             goto fail;
         }
@@ -3401,22 +3418,13 @@ g_dbus_message_set_signature (GDBusMessage  *message,
 const gchar *
 g_dbus_message_get_arg0 (GDBusMessage  *message)
 {
-  const gchar *ret;
-
   g_return_val_if_fail (G_IS_DBUS_MESSAGE (message), NULL);
 
-  ret = NULL;
+  if (message->arg0_cache != NULL &&
+      g_variant_is_of_type (message->arg0_cache, G_VARIANT_TYPE_STRING))
+    return g_variant_get_string (message->arg0_cache, NULL);
 
-  if (message->body != NULL && g_variant_is_of_type (message->body, G_VARIANT_TYPE_TUPLE))
-    {
-      GVariant *item;
-      item = g_variant_get_child_value (message->body, 0);
-      if (g_variant_is_of_type (item, G_VARIANT_TYPE_STRING))
-        ret = g_variant_get_string (item, NULL);
-      g_variant_unref (item);
-    }
-
-  return ret;
+  return NULL;
 }
 
 /* ---------------------------------------------------------------------------------------------------- */
@@ -3859,6 +3867,7 @@ g_dbus_message_copy (GDBusMessage  *message,
    * to just ref (as opposed to deep-copying) the GVariant instances
    */
   ret->body = message->body != NULL ? g_variant_ref (message->body) : NULL;
+  ret->arg0_cache = message->arg0_cache != NULL ? g_variant_ref (message->arg0_cache) : NULL;
   g_hash_table_iter_init (&iter, message->headers);
   while (g_hash_table_iter_next (&iter, &header_key, (gpointer) &header_value))
     g_hash_table_insert (ret->headers, header_key, g_variant_ref (header_value));
-- 
GitLab


From b6a68c0e42d3e28d5e6abdb364dca959720c7f99 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Fri, 8 Mar 2024 14:19:46 +0000
Subject: [PATCH 02/17] tests: Add a data-driven test for signal subscriptions

This somewhat duplicates test_connection_signals(), but is easier to
extend to cover different scenarios.

Each scenario is tested three times: once with lower-level
GDBusConnection APIs, once with the higher-level GDBusProxy (which
cannot implement all of the subscription scenarios, so some message
counts are lower), and once with both (to check that delivery of the
same message to multiple destinations is handled appropriately).

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 938 ++++++++++++++++++++++++++++++++++++
 gio/tests/meson.build       |   4 +
 2 files changed, 942 insertions(+)
 create mode 100644 gio/tests/gdbus-subscribe.c

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
new file mode 100644
index 0000000000..3f53e1d7f8
--- /dev/null
+++ b/gio/tests/gdbus-subscribe.c
@@ -0,0 +1,938 @@
+/*
+ * Copyright 2024 Collabora Ltd.
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include <gio/gio.h>
+
+#include "gdbus-tests.h"
+
+#define DBUS_SERVICE_DBUS "org.freedesktop.DBus"
+#define DBUS_PATH_DBUS "/org/freedesktop/DBus"
+#define DBUS_INTERFACE_DBUS DBUS_SERVICE_DBUS
+
+/* A signal that each connection emits to indicate that it has finished
+ * emitting other signals */
+#define FINISHED_PATH "/org/gtk/Test/Finished"
+#define FINISHED_INTERFACE "org.gtk.Test.Finished"
+#define FINISHED_SIGNAL "Finished"
+
+/* A signal emitted during testing */
+#define EXAMPLE_PATH "/org/gtk/GDBus/ExampleInterface"
+#define EXAMPLE_INTERFACE "org.gtk.GDBus.ExampleInterface"
+#define FOO_SIGNAL "Foo"
+
+/* Log @s in a debug message. */
+static inline const char *
+nonnull (const char *s,
+         const char *if_null)
+{
+  return (s == NULL) ? if_null : s;
+}
+
+typedef enum
+{
+  TEST_CONN_NONE,
+  TEST_CONN_FIRST,
+  /* A connection that subscribes to signals */
+  TEST_CONN_SUBSCRIBER = TEST_CONN_FIRST,
+  /* A mockup of a legitimate service */
+  TEST_CONN_SERVICE,
+  /* A mockup of a second legitimate service */
+  TEST_CONN_SERVICE2,
+  /* A connection that tries to trick @subscriber into processing its signals
+   * as if they came from @service */
+  TEST_CONN_ATTACKER,
+  NUM_TEST_CONNS
+} TestConn;
+
+static const char * const test_conn_descriptions[NUM_TEST_CONNS] =
+{
+  "(unused)",
+  "subscriber",
+  "service",
+  "service 2",
+  "attacker"
+};
+
+typedef enum
+{
+  SUBSCRIPTION_MODE_CONN,
+  SUBSCRIPTION_MODE_PROXY,
+  SUBSCRIPTION_MODE_PARALLEL
+} SubscriptionMode;
+
+typedef struct
+{
+  GDBusProxy *received_by_proxy;
+  TestConn sender;
+  char *path;
+  char *iface;
+  char *member;
+  GVariant *parameters;
+  char *arg0;
+  guint32 step;
+} ReceivedMessage;
+
+static void
+received_message_free (ReceivedMessage *self)
+{
+
+  g_clear_object (&self->received_by_proxy);
+  g_free (self->path);
+  g_free (self->iface);
+  g_free (self->member);
+  g_clear_pointer (&self->parameters, g_variant_unref);
+  g_free (self->arg0);
+  g_free (self);
+}
+
+typedef struct
+{
+  TestConn sender;
+  TestConn unicast_to;
+  const char *path;
+  const char *iface;
+  const char *member;
+  const char *arg0;
+  guint received_by_conn;
+  guint received_by_proxy;
+} TestEmitSignal;
+
+typedef struct
+{
+  TestConn sender;
+  const char *path;
+  const char *iface;
+  const char *member;
+  const char *arg0;
+  GDBusSignalFlags flags;
+} TestSubscribe;
+
+typedef enum
+{
+  TEST_ACTION_NONE = 0,
+  TEST_ACTION_SUBSCRIBE,
+  TEST_ACTION_EMIT_SIGNAL,
+} TestAction;
+
+typedef struct
+{
+  TestAction action;
+  union {
+    TestEmitSignal signal;
+    TestSubscribe subscribe;
+  } u;
+} TestStep;
+
+/* Arbitrary, extend as necessary to accommodate the longest test */
+#define MAX_TEST_STEPS 10
+
+typedef struct
+{
+  const char *description;
+  TestStep steps[MAX_TEST_STEPS];
+} TestPlan;
+
+static const TestPlan plan_simple =
+{
+  .description = "A broadcast is only received after subscribing to it",
+  .steps = {
+    {
+      /* We don't receive a signal if we haven't subscribed yet */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      /* Now it works */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        /* The proxy can't be used in this case, because it needs
+         * a bus name to subscribe to */
+        .received_by_proxy = 0
+      },
+    },
+  },
+};
+
+static const TestPlan plan_broadcast_from_anyone =
+{
+  .description = "A subscription with NULL sender accepts broadcast and unicast",
+  .steps = {
+    {
+      /* Subscriber wants to receive signals from anyone */
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      /* First service sends a broadcast */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* Second service also sends a broadcast */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE2,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* First service sends a unicast signal */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .unicast_to = TEST_CONN_SUBSCRIBER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* Second service also sends a unicast signal */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE2,
+        .unicast_to = TEST_CONN_SUBSCRIBER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        .received_by_proxy = 0
+      },
+    },
+  },
+};
+
+static const TestPlan plan_match_twice =
+{
+  .description = "A message matching more than one subscription is received "
+                 "once per subscription",
+  .steps = {
+    {
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .path = EXAMPLE_PATH,
+      },
+    },
+    {
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 4,
+        /* Only the first and last work with GDBusProxy */
+        .received_by_proxy = 2
+      },
+    },
+  },
+};
+
+static const TestPlan plan_limit_by_unique_name =
+{
+  .description = "A subscription via a unique name only accepts messages "
+                 "sent by that same unique name",
+  .steps = {
+    {
+      /* Subscriber wants to receive signals from service */
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      /* Attacker wants to trick subscriber into thinking that service
+       * sent a signal */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* Attacker tries harder, by sending a signal unicast directly to
+       * the subscriber */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .unicast_to = TEST_CONN_SUBSCRIBER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* When the real service sends a signal, it should still get through */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        .received_by_proxy = 1
+      },
+    },
+  },
+};
+
+typedef struct
+{
+  const TestPlan *plan;
+  SubscriptionMode mode;
+  GError *error;
+  /* (element-type ReceivedMessage) */
+  GPtrArray *received;
+  /* conns[TEST_CONN_NONE] is unused and remains NULL */
+  GDBusConnection *conns[NUM_TEST_CONNS];
+  /* Proxies on conns[TEST_CONN_SUBSCRIBER] */
+  GPtrArray *proxies;
+  /* unique_names[TEST_CONN_NONE] is unused and remains NULL */
+  const char *unique_names[NUM_TEST_CONNS];
+  /* finished[TEST_CONN_NONE] is unused and remains FALSE */
+  gboolean finished[NUM_TEST_CONNS];
+  /* Remains 0 for any step that is not a subscription */
+  guint subscriptions[MAX_TEST_STEPS];
+  /* Number of times the signal from step n was received */
+  guint received_by_conn[MAX_TEST_STEPS];
+  /* Number of times the signal from step n was received */
+  guint received_by_proxy[MAX_TEST_STEPS];
+  guint finished_subscription;
+} Fixture;
+
+/* Wait for asynchronous messages from @conn to have been processed
+ * by the message bus, as a sequence point so that we can make
+ * "happens before" and "happens after" assertions relative to this.
+ * The easiest way to achieve this is to call a message bus method that has
+ * no arguments and wait for it to return: because the message bus processes
+ * messages in-order, anything we sent before this must have been processed
+ * by the time this call arrives. */
+static void
+connection_wait_for_bus (GDBusConnection *conn)
+{
+  GError *error = NULL;
+  GVariant *call_result;
+
+  call_result = g_dbus_connection_call_sync (conn,
+                                             DBUS_SERVICE_DBUS,
+                                             DBUS_PATH_DBUS,
+                                             DBUS_INTERFACE_DBUS,
+                                             "GetId",
+                                             NULL,   /* arguments */
+                                             NULL,   /* result type */
+                                             G_DBUS_CALL_FLAGS_NONE,
+                                             -1,
+                                             NULL,
+                                             &error);
+  g_assert_no_error (error);
+  g_assert_nonnull (call_result);
+  g_variant_unref (call_result);
+}
+
+/*
+ * Called when the subscriber receives a message from any connection
+ * announcing that it has emitted all the signals that it plans to emit.
+ */
+static void
+subscriber_finished_cb (GDBusConnection *conn,
+                        const char      *sender_name,
+                        const char      *path,
+                        const char      *iface,
+                        const char      *member,
+                        GVariant        *parameters,
+                        void            *user_data)
+{
+  Fixture *f = user_data;
+  GDBusConnection *subscriber = f->conns[TEST_CONN_SUBSCRIBER];
+  guint i;
+
+  g_assert_true (conn == subscriber);
+
+  for (i = TEST_CONN_FIRST; i < G_N_ELEMENTS (f->conns); i++)
+    {
+      if (g_str_equal (sender_name, f->unique_names[i]))
+        {
+          g_assert_false (f->finished[i]);
+          f->finished[i] = TRUE;
+
+          g_test_message ("Received Finished signal from %s %s",
+                          test_conn_descriptions[i], sender_name);
+          return;
+        }
+    }
+
+  g_error ("Received Finished signal from unknown sender %s", sender_name);
+}
+
+/*
+ * Called when we receive a signal, either via the GDBusProxy (proxy != NULL)
+ * or via the GDBusConnection (proxy == NULL).
+ */
+static void
+fixture_received_signal (Fixture    *f,
+                         GDBusProxy *proxy,
+                         const char *sender_name,
+                         const char *path,
+                         const char *iface,
+                         const char *member,
+                         GVariant   *parameters)
+{
+  guint i;
+  ReceivedMessage *received;
+
+  /* Ignore the Finished signal if it matches a wildcard subscription */
+  if (g_str_equal (member, FINISHED_SIGNAL))
+    return;
+
+  received = g_new0 (ReceivedMessage, 1);
+
+  if (proxy != NULL)
+    received->received_by_proxy = g_object_ref (proxy);
+  else
+    received->received_by_proxy = NULL;
+
+  received->path = g_strdup (path);
+  received->iface = g_strdup (iface);
+  received->member = g_strdup (member);
+  received->parameters = g_variant_ref (parameters);
+
+  for (i = TEST_CONN_FIRST; i < G_N_ELEMENTS (f->conns); i++)
+    {
+      if (g_str_equal (sender_name, f->unique_names[i]))
+        {
+          received->sender = i;
+          g_assert_false (f->finished[i]);
+          break;
+        }
+    }
+
+  g_assert_cmpint (received->sender, !=, TEST_CONN_NONE);
+
+  g_test_message ("Signal received from %s %s via %s",
+                  test_conn_descriptions[received->sender],
+                  sender_name,
+                  proxy != NULL ? "proxy" : "connection");
+  g_test_message ("\tPath: %s", path);
+  g_test_message ("\tInterface: %s", iface);
+  g_test_message ("\tMember: %s", member);
+
+  if (g_variant_is_of_type (parameters, G_VARIANT_TYPE ("(su)")))
+    {
+      g_variant_get (parameters, "(su)", &received->arg0, &received->step);
+      g_test_message ("\tString argument 0: %s", received->arg0);
+      g_test_message ("\tSent in step: %u", received->step);
+    }
+  else
+    {
+      g_assert_cmpstr (g_variant_get_type_string (parameters), ==, "(uu)");
+      g_variant_get (parameters, "(uu)", NULL, &received->step);
+      g_test_message ("\tArgument 0: (not a string)");
+      g_test_message ("\tSent in step: %u", received->step);
+    }
+
+  g_ptr_array_add (f->received, g_steal_pointer (&received));
+}
+
+static void
+proxy_signal_cb (GDBusProxy *proxy,
+                 const char *sender_name,
+                 const char *member,
+                 GVariant   *parameters,
+                 void       *user_data)
+{
+  Fixture *f = user_data;
+
+  fixture_received_signal (f, proxy, sender_name,
+                           g_dbus_proxy_get_object_path (proxy),
+                           g_dbus_proxy_get_interface_name (proxy),
+                           member, parameters);
+}
+
+static void
+subscribed_signal_cb (GDBusConnection *conn,
+                      const char      *sender_name,
+                      const char      *path,
+                      const char      *iface,
+                      const char      *member,
+                      GVariant        *parameters,
+                      void            *user_data)
+{
+  Fixture *f = user_data;
+  GDBusConnection *subscriber = f->conns[TEST_CONN_SUBSCRIBER];
+
+  g_assert_true (conn == subscriber);
+
+  fixture_received_signal (f, NULL, sender_name, path, iface, member, parameters);
+}
+
+static void
+fixture_subscribe (Fixture             *f,
+                   const TestSubscribe *subscribe,
+                   guint                step_number)
+{
+  GDBusConnection *subscriber = f->conns[TEST_CONN_SUBSCRIBER];
+  const char *sender;
+
+  if (subscribe->sender != TEST_CONN_NONE)
+    {
+      sender = f->unique_names[subscribe->sender];
+      g_test_message ("\tSender: %s %s",
+                      test_conn_descriptions[subscribe->sender],
+                      sender);
+    }
+  else
+    {
+      sender = NULL;
+      g_test_message ("\tSender: (any)");
+    }
+
+  g_test_message ("\tPath: %s", nonnull (subscribe->path, "(any)"));
+  g_test_message ("\tInterface: %s",
+                  nonnull (subscribe->iface, "(any)"));
+  g_test_message ("\tMember: %s",
+                  nonnull (subscribe->member, "(any)"));
+  g_test_message ("\tString argument 0: %s",
+                  nonnull (subscribe->arg0, "(any)"));
+  g_test_message ("\tFlags: %x", subscribe->flags);
+
+  if (f->mode != SUBSCRIPTION_MODE_PROXY)
+    {
+      /* CONN or PARALLEL */
+      guint id;
+
+      g_test_message ("\tSubscribing via connection");
+      id = g_dbus_connection_signal_subscribe (subscriber,
+                                               sender,
+                                               subscribe->iface,
+                                               subscribe->member,
+                                               subscribe->path,
+                                               subscribe->arg0,
+                                               subscribe->flags,
+                                               subscribed_signal_cb,
+                                               f, NULL);
+      g_assert_cmpuint (id, !=, 0);
+      f->subscriptions[step_number] = id;
+    }
+
+  if (f->mode != SUBSCRIPTION_MODE_CONN)
+    {
+      /* PROXY or PARALLEL */
+
+      if (sender == NULL)
+        {
+          g_test_message ("\tCannot subscribe via proxy: no bus name");
+        }
+      else if (subscribe->path == NULL)
+        {
+          g_test_message ("\tCannot subscribe via proxy: no path");
+        }
+      else if (subscribe->iface == NULL)
+        {
+          g_test_message ("\tCannot subscribe via proxy: no interface");
+        }
+      else
+        {
+          GDBusProxy *proxy;
+
+          g_test_message ("\tSubscribing via proxy");
+          proxy = g_dbus_proxy_new_sync (subscriber,
+                                         (G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES
+                                          | G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START),
+                                         NULL,    /* GDBusInterfaceInfo */
+                                         sender,
+                                         subscribe->path,
+                                         subscribe->iface,
+                                         NULL,    /* GCancellable */
+                                         &f->error);
+          g_assert_no_error (f->error);
+          g_assert_nonnull (proxy);
+          g_signal_connect (proxy, "g-signal", G_CALLBACK (proxy_signal_cb), f);
+          g_ptr_array_add (f->proxies, g_steal_pointer (&proxy));
+        }
+    }
+
+  /* As in setup(), we need to wait for AddMatch to happen. */
+  g_test_message ("Waiting for AddMatch to be processed");
+  connection_wait_for_bus (subscriber);
+}
+
+static void
+fixture_emit_signal (Fixture              *f,
+                     const TestEmitSignal *signal,
+                     guint                 step_number)
+{
+  GVariant *body;
+  const char *destination;
+  gboolean ok;
+
+  g_test_message ("\tSender: %s",
+                  test_conn_descriptions[signal->sender]);
+
+  if (signal->unicast_to != TEST_CONN_NONE)
+    {
+      destination = f->unique_names[signal->unicast_to];
+      g_test_message ("\tDestination: %s %s",
+                      test_conn_descriptions[signal->unicast_to],
+                      destination);
+    }
+  else
+    {
+      destination = NULL;
+      g_test_message ("\tDestination: (broadcast)");
+    }
+
+  g_assert_nonnull (signal->path);
+  g_test_message ("\tPath: %s", signal->path);
+  g_assert_nonnull (signal->iface);
+  g_test_message ("\tInterface: %s", signal->iface);
+  g_assert_nonnull (signal->member);
+  g_test_message ("\tMember: %s", signal->member);
+
+  /* If arg0 is non-NULL, put it in the message's argument 0.
+   * Otherwise put something that will not match any arg0.
+   * Either way, put the sequence number in argument 1 so we can
+   * correlate sent messages with received messages later. */
+  if (signal->arg0 != NULL)
+    {
+      g_test_message ("\tString argument 0: %s", signal->arg0);
+      /* floating */
+      body = g_variant_new ("(su)", signal->arg0, (guint32) step_number);
+    }
+  else
+    {
+      g_test_message ("\tArgument 0: (not a string)");
+      body = g_variant_new ("(uu)", (guint32) 0, (guint32) step_number);
+    }
+
+  ok = g_dbus_connection_emit_signal (f->conns[signal->sender],
+                                      destination,
+                                      signal->path,
+                                      signal->iface,
+                                      signal->member,
+                                      /* steals floating reference */
+                                      g_steal_pointer (&body),
+                                      &f->error);
+  g_assert_no_error (f->error);
+  g_assert_true (ok);
+
+  /* Emitting the signal is asynchronous, so if we want subsequent steps
+   * to be guaranteed to happen after the signal from the message bus's
+   * perspective, we have to do a round-trip to the message bus to sync up. */
+  g_test_message ("Waiting for signal to reach message bus");
+  connection_wait_for_bus (f->conns[signal->sender]);
+}
+
+static void
+fixture_run_plan (Fixture          *f,
+                  const TestPlan   *plan,
+                  SubscriptionMode  mode)
+{
+  guint i;
+
+  G_STATIC_ASSERT (G_N_ELEMENTS (plan->steps) == G_N_ELEMENTS (f->subscriptions));
+  G_STATIC_ASSERT (G_N_ELEMENTS (plan->steps) == G_N_ELEMENTS (f->received_by_conn));
+  G_STATIC_ASSERT (G_N_ELEMENTS (plan->steps) == G_N_ELEMENTS (f->received_by_proxy));
+
+  f->mode = mode;
+  f->plan = plan;
+
+  g_test_summary (plan->description);
+
+  for (i = 0; i < G_N_ELEMENTS (plan->steps); i++)
+    {
+      const TestStep *step = &plan->steps[i];
+
+      switch (step->action)
+        {
+          case TEST_ACTION_SUBSCRIBE:
+            g_test_message ("Step %u: adding subscription", i);
+            fixture_subscribe (f, &step->u.subscribe, i);
+            break;
+
+          case TEST_ACTION_EMIT_SIGNAL:
+            g_test_message ("Step %u: emitting signal", i);
+            fixture_emit_signal (f, &step->u.signal, i);
+            break;
+
+          case TEST_ACTION_NONE:
+            /* Padding to fill the rest of the array, do nothing */
+            break;
+
+          default:
+            g_return_if_reached ();
+        }
+    }
+
+  /* Now that we have done everything we wanted to do, emit Finished
+   * from each connection. */
+  for (i = TEST_CONN_FIRST; i < G_N_ELEMENTS (f->conns); i++)
+    {
+      gboolean ok;
+
+      ok = g_dbus_connection_emit_signal (f->conns[i],
+                                          NULL,
+                                          FINISHED_PATH,
+                                          FINISHED_INTERFACE,
+                                          FINISHED_SIGNAL,
+                                          NULL,
+                                          &f->error);
+      g_assert_no_error (f->error);
+      g_assert_true (ok);
+    }
+
+  /* Wait until we have seen the Finished signal from each sender */
+  while (TRUE)
+    {
+      gboolean all_finished = TRUE;
+
+      for (i = TEST_CONN_FIRST; i < G_N_ELEMENTS (f->conns); i++)
+        all_finished = all_finished && f->finished[i];
+
+      if (all_finished)
+        break;
+
+      g_main_context_iteration (NULL, TRUE);
+    }
+
+  /* Assert that the correct things happened before each Finished signal */
+  for (i = 0; i < f->received->len; i++)
+    {
+      const ReceivedMessage *received = g_ptr_array_index (f->received, i);
+
+      g_assert_cmpuint (received->step, <, G_N_ELEMENTS (f->received_by_conn));
+      g_assert_cmpuint (received->step, <, G_N_ELEMENTS (f->received_by_proxy));
+      g_assert_cmpint (plan->steps[received->step].action,
+                       ==, TEST_ACTION_EMIT_SIGNAL);
+
+      if (received->received_by_proxy != NULL)
+        f->received_by_proxy[received->step] += 1;
+      else
+        f->received_by_conn[received->step] += 1;
+    }
+
+  for (i = 0; i < G_N_ELEMENTS (plan->steps); i++)
+    {
+      const TestStep *step = &plan->steps[i];
+
+      if (step->action == TEST_ACTION_EMIT_SIGNAL)
+        {
+          const TestEmitSignal *signal = &plan->steps[i].u.signal;
+
+          if (mode != SUBSCRIPTION_MODE_PROXY)
+            {
+              g_test_message ("Signal from step %u was received %u times by "
+                              "GDBusConnection, expected %u",
+                              i, f->received_by_conn[i], signal->received_by_conn);
+              g_assert_cmpuint (f->received_by_conn[i], ==, signal->received_by_conn);
+            }
+          else
+            {
+              g_assert_cmpuint (f->received_by_conn[i], ==, 0);
+            }
+
+          if (mode != SUBSCRIPTION_MODE_CONN)
+            {
+              g_test_message ("Signal from step %u was received %u times by "
+                              "GDBusProxy, expected %u",
+                              i, f->received_by_proxy[i], signal->received_by_proxy);
+              g_assert_cmpuint (f->received_by_proxy[i], ==, signal->received_by_proxy);
+            }
+          else
+            {
+              g_assert_cmpuint (f->received_by_proxy[i], ==, 0);
+            }
+        }
+    }
+}
+
+static void
+setup (Fixture *f,
+       G_GNUC_UNUSED const void *context)
+{
+  GDBusConnection *subscriber;
+  guint i;
+
+  session_bus_up ();
+
+  f->proxies = g_ptr_array_new_full (MAX_TEST_STEPS, g_object_unref);
+  f->received = g_ptr_array_new_full (MAX_TEST_STEPS,
+                                      (GDestroyNotify) received_message_free);
+
+  for (i = TEST_CONN_FIRST; i < G_N_ELEMENTS (f->conns); i++)
+    {
+      f->conns[i] = _g_bus_get_priv (G_BUS_TYPE_SESSION, NULL, &f->error);
+      g_assert_no_error (f->error);
+      g_assert_nonnull (f->conns[i]);
+
+      f->unique_names[i] = g_dbus_connection_get_unique_name (f->conns[i]);
+      g_assert_nonnull (f->unique_names[i]);
+      g_test_message ("%s is %s",
+                      test_conn_descriptions[i],
+                      f->unique_names[i]);
+    }
+
+  subscriber = f->conns[TEST_CONN_SUBSCRIBER];
+
+  /* Used to wait for all connections to finish sending whatever they
+   * wanted to send */
+  f->finished_subscription = g_dbus_connection_signal_subscribe (subscriber,
+                                                                 NULL,
+                                                                 FINISHED_INTERFACE,
+                                                                 FINISHED_SIGNAL,
+                                                                 FINISHED_PATH,
+                                                                 NULL,
+                                                                 G_DBUS_SIGNAL_FLAGS_NONE,
+                                                                 subscriber_finished_cb,
+                                                                 f, NULL);
+  /* AddMatch is sent asynchronously, so we don't know how
+   * soon it will be processed. Before emitting signals, we
+   * need to wait for the message bus to get as far as processing
+   * AddMatch. */
+  g_test_message ("Waiting for AddMatch to be processed");
+  connection_wait_for_bus (subscriber);
+}
+
+static void
+test_conn_subscribe (Fixture *f,
+                     const void *context)
+{
+  fixture_run_plan (f, context, SUBSCRIPTION_MODE_CONN);
+}
+
+static void
+test_proxy_subscribe (Fixture *f,
+                      const void *context)
+{
+  fixture_run_plan (f, context, SUBSCRIPTION_MODE_PROXY);
+}
+
+static void
+test_parallel_subscribe (Fixture *f,
+                         const void *context)
+{
+  fixture_run_plan (f, context, SUBSCRIPTION_MODE_PARALLEL);
+}
+
+static void
+teardown (Fixture *f,
+          G_GNUC_UNUSED const void *context)
+{
+  GDBusConnection *subscriber = f->conns[TEST_CONN_SUBSCRIBER];
+  guint i;
+
+  g_ptr_array_unref (f->proxies);
+
+  if (f->finished_subscription != 0)
+    g_dbus_connection_signal_unsubscribe (subscriber, f->finished_subscription);
+
+  for (i = 0; i < G_N_ELEMENTS (f->subscriptions); i++)
+    {
+      if (f->subscriptions[i] != 0)
+        g_dbus_connection_signal_unsubscribe (subscriber, f->subscriptions[i]);
+    }
+
+  g_ptr_array_unref (f->received);
+
+  for (i = TEST_CONN_FIRST; i < G_N_ELEMENTS (f->conns); i++)
+    g_clear_object (&f->conns[i]);
+
+  g_clear_error (&f->error);
+
+  session_bus_down ();
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
+
+  g_test_dbus_unset ();
+
+#define ADD_SUBSCRIBE_TEST(name) \
+  do { \
+    g_test_add ("/gdbus/subscribe/conn/" #name, \
+                Fixture, &plan_ ## name, \
+                setup, test_conn_subscribe, teardown); \
+    g_test_add ("/gdbus/subscribe/proxy/" #name, \
+                Fixture, &plan_ ## name, \
+                setup, test_proxy_subscribe, teardown); \
+    g_test_add ("/gdbus/subscribe/parallel/" #name, \
+                Fixture, &plan_ ## name, \
+                setup, test_parallel_subscribe, teardown); \
+  } while (0)
+
+  ADD_SUBSCRIBE_TEST (simple);
+  ADD_SUBSCRIBE_TEST (broadcast_from_anyone);
+  ADD_SUBSCRIBE_TEST (match_twice);
+  ADD_SUBSCRIBE_TEST (limit_by_unique_name);
+
+  return g_test_run();
+}
diff --git a/gio/tests/meson.build b/gio/tests/meson.build
index 4ef3343ab3..298f9b4cb8 100644
--- a/gio/tests/meson.build
+++ b/gio/tests/meson.build
@@ -463,6 +463,10 @@ if host_machine.system() != 'windows'
         'extra_sources' : extra_sources,
         'extra_programs': extra_programs,
       },
+      'gdbus-subscribe' : {
+        'extra_sources' : extra_sources,
+        'extra_programs': extra_programs,
+      },
       'gdbus-test-codegen' : {
         'extra_sources' : [extra_sources, gdbus_test_codegen_generated, gdbus_test_codegen_generated_interface_info],
         'c_args' : ['-DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_32'],
-- 
GitLab


From 2a128c7ce058aae495a7fe5a65c6ba83521409a0 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Fri, 8 Mar 2024 19:28:15 +0000
Subject: [PATCH 03/17] tests: Add support for subscribing to signals from a
 well-known name

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 133 ++++++++++++++++++++++++++++++++++--
 1 file changed, 126 insertions(+), 7 deletions(-)

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
index 3f53e1d7f8..3d2a14e03b 100644
--- a/gio/tests/gdbus-subscribe.c
+++ b/gio/tests/gdbus-subscribe.c
@@ -7,6 +7,9 @@
 
 #include "gdbus-tests.h"
 
+/* From the D-Bus Specification */
+#define DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER 1
+
 #define DBUS_SERVICE_DBUS "org.freedesktop.DBus"
 #define DBUS_PATH_DBUS "/org/freedesktop/DBus"
 #define DBUS_INTERFACE_DBUS DBUS_SERVICE_DBUS
@@ -22,6 +25,9 @@
 #define EXAMPLE_INTERFACE "org.gtk.GDBus.ExampleInterface"
 #define FOO_SIGNAL "Foo"
 
+#define ALREADY_OWNED_NAME "org.gtk.Test.AlreadyOwned"
+#define OWNED_LATER_NAME "org.gtk.Test.OwnedLater"
+
 /* Log @s in a debug message. */
 static inline const char *
 nonnull (const char *s,
@@ -101,7 +107,8 @@ typedef struct
 
 typedef struct
 {
-  TestConn sender;
+  const char *string_sender;
+  TestConn unique_sender;
   const char *path;
   const char *iface;
   const char *member;
@@ -109,11 +116,18 @@ typedef struct
   GDBusSignalFlags flags;
 } TestSubscribe;
 
+typedef struct
+{
+  const char *name;
+  TestConn owner;
+} TestOwnName;
+
 typedef enum
 {
   TEST_ACTION_NONE = 0,
   TEST_ACTION_SUBSCRIBE,
   TEST_ACTION_EMIT_SIGNAL,
+  TEST_ACTION_OWN_NAME,
 } TestAction;
 
 typedef struct
@@ -122,6 +136,7 @@ typedef struct
   union {
     TestEmitSignal signal;
     TestSubscribe subscribe;
+    TestOwnName own_name;
   } u;
 } TestStep;
 
@@ -247,7 +262,7 @@ static const TestPlan plan_match_twice =
     {
       .action = TEST_ACTION_SUBSCRIBE,
       .u.subscribe = {
-        .sender = TEST_CONN_SERVICE,
+        .unique_sender = TEST_CONN_SERVICE,
         .path = EXAMPLE_PATH,
         .iface = EXAMPLE_INTERFACE,
       },
@@ -267,7 +282,7 @@ static const TestPlan plan_match_twice =
     {
       .action = TEST_ACTION_SUBSCRIBE,
       .u.subscribe = {
-        .sender = TEST_CONN_SERVICE,
+        .unique_sender = TEST_CONN_SERVICE,
         .path = EXAMPLE_PATH,
         .iface = EXAMPLE_INTERFACE,
       },
@@ -296,7 +311,7 @@ static const TestPlan plan_limit_by_unique_name =
       /* Subscriber wants to receive signals from service */
       .action = TEST_ACTION_SUBSCRIBE,
       .u.subscribe = {
-        .sender = TEST_CONN_SERVICE,
+        .unique_sender = TEST_CONN_SERVICE,
         .path = EXAMPLE_PATH,
         .iface = EXAMPLE_INTERFACE,
       },
@@ -343,6 +358,62 @@ static const TestPlan plan_limit_by_unique_name =
   },
 };
 
+static const TestPlan plan_limit_by_well_known_name =
+{
+  .description = "A subscription via a well-known name only accepts messages "
+                 "sent by the owner of that well-known name",
+  .steps = {
+    {
+      /* Service already owns one name */
+      .action = TEST_ACTION_OWN_NAME,
+      .u.own_name = {
+        .name = ALREADY_OWNED_NAME,
+        .owner = TEST_CONN_SERVICE
+      },
+    },
+    {
+      /* Subscriber wants to receive signals from service */
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .string_sender = ALREADY_OWNED_NAME,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      /* Subscriber wants to receive signals from service by another name */
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .string_sender = OWNED_LATER_NAME,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      /* Service claims another name */
+      .action = TEST_ACTION_OWN_NAME,
+      .u.own_name = {
+        .name = OWNED_LATER_NAME,
+        .owner = TEST_CONN_SERVICE
+      },
+    },
+    {
+      /* Now the subscriber gets this signal twice, once for each
+       * subscription; and similarly each of the two proxies gets this
+       * signal twice */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 2,
+        .received_by_proxy = 2
+      },
+    },
+  },
+};
+
 typedef struct
 {
   const TestPlan *plan;
@@ -540,11 +611,16 @@ fixture_subscribe (Fixture             *f,
   GDBusConnection *subscriber = f->conns[TEST_CONN_SUBSCRIBER];
   const char *sender;
 
-  if (subscribe->sender != TEST_CONN_NONE)
+  if (subscribe->string_sender != NULL)
+    {
+      sender = subscribe->string_sender;
+      g_test_message ("\tSender: %s", sender);
+    }
+  else if (subscribe->unique_sender != TEST_CONN_NONE)
     {
-      sender = f->unique_names[subscribe->sender];
+      sender = f->unique_names[subscribe->unique_sender];
       g_test_message ("\tSender: %s %s",
-                      test_conn_descriptions[subscribe->sender],
+                      test_conn_descriptions[subscribe->unique_sender],
                       sender);
     }
   else
@@ -689,6 +765,43 @@ fixture_emit_signal (Fixture              *f,
   connection_wait_for_bus (f->conns[signal->sender]);
 }
 
+static void
+fixture_own_name (Fixture *f,
+                  const TestOwnName *own_name)
+{
+  GVariant *call_result;
+  guint32 flags;
+  guint32 result_code;
+
+  g_test_message ("\tName: %s", own_name->name);
+  g_test_message ("\tOwner: %s",
+                  test_conn_descriptions[own_name->owner]);
+
+  /* For simplicity, we do this via a direct bus call rather than
+   * using g_bus_own_name_on_connection(). The flags in
+   * GBusNameOwnerFlags are numerically equal to those in the
+   * D-Bus wire protocol. */
+  flags = G_BUS_NAME_OWNER_FLAGS_DO_NOT_QUEUE;
+  call_result = g_dbus_connection_call_sync (f->conns[own_name->owner],
+                                             DBUS_SERVICE_DBUS,
+                                             DBUS_PATH_DBUS,
+                                             DBUS_INTERFACE_DBUS,
+                                             "RequestName",
+                                             g_variant_new ("(su)",
+                                                           own_name->name,
+                                                           flags),
+                                             G_VARIANT_TYPE ("(u)"),
+                                             G_DBUS_CALL_FLAGS_NONE,
+                                             -1,
+                                             NULL,
+                                             &f->error);
+  g_assert_no_error (f->error);
+  g_assert_nonnull (call_result);
+  g_variant_get (call_result, "(u)", &result_code);
+  g_assert_cmpuint (result_code, ==, DBUS_REQUEST_NAME_REPLY_PRIMARY_OWNER);
+  g_variant_unref (call_result);
+}
+
 static void
 fixture_run_plan (Fixture          *f,
                   const TestPlan   *plan,
@@ -721,6 +834,11 @@ fixture_run_plan (Fixture          *f,
             fixture_emit_signal (f, &step->u.signal, i);
             break;
 
+          case TEST_ACTION_OWN_NAME:
+            g_test_message ("Step %u: claiming bus name", i);
+            fixture_own_name (f, &step->u.own_name);
+            break;
+
           case TEST_ACTION_NONE:
             /* Padding to fill the rest of the array, do nothing */
             break;
@@ -933,6 +1051,7 @@ main (int   argc,
   ADD_SUBSCRIBE_TEST (broadcast_from_anyone);
   ADD_SUBSCRIBE_TEST (match_twice);
   ADD_SUBSCRIBE_TEST (limit_by_unique_name);
+  ADD_SUBSCRIBE_TEST (limit_by_well_known_name);
 
   return g_test_run();
 }
-- 
GitLab


From dfe0515edea5490204e189209b3159fba9164d1e Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Fri, 8 Mar 2024 19:44:03 +0000
Subject: [PATCH 04/17] tests: Add a test-case for what happens if a unique
 name doesn't exist

On GNOME/glib#3268 there was some concern about whether this would
allow an attacker to send signals and have them be matched to a
GDBusProxy in this situation, but it seems that was a false alarm.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 48 +++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
index 3d2a14e03b..350ec9f52f 100644
--- a/gio/tests/gdbus-subscribe.c
+++ b/gio/tests/gdbus-subscribe.c
@@ -358,6 +358,53 @@ static const TestPlan plan_limit_by_unique_name =
   },
 };
 
+static const TestPlan plan_nonexistent_unique_name =
+{
+  .description = "A subscription via a unique name that doesn't exist "
+                 "accepts no messages",
+  .steps = {
+    {
+      /* Subscriber wants to receive signals from service */
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        /* This relies on the implementation detail that the dbus-daemon
+         * (and presumably other bus implementations) never actually generates
+         * a unique name in this format */
+        .string_sender = ":0.this.had.better.not.exist",
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+      },
+    },
+    {
+      /* Attacker wants to trick subscriber into thinking that service
+       * sent a signal */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* Attacker tries harder, by sending a signal unicast directly to
+       * the subscriber */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .unicast_to = TEST_CONN_SUBSCRIBER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+  },
+};
+
 static const TestPlan plan_limit_by_well_known_name =
 {
   .description = "A subscription via a well-known name only accepts messages "
@@ -1051,6 +1098,7 @@ main (int   argc,
   ADD_SUBSCRIBE_TEST (broadcast_from_anyone);
   ADD_SUBSCRIBE_TEST (match_twice);
   ADD_SUBSCRIBE_TEST (limit_by_unique_name);
+  ADD_SUBSCRIBE_TEST (nonexistent_unique_name);
   ADD_SUBSCRIBE_TEST (limit_by_well_known_name);
 
   return g_test_run();
-- 
GitLab


From 0df62f58d0a729a571f1e1df2c96c8cb609d77c8 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Fri, 8 Mar 2024 20:10:29 +0000
Subject: [PATCH 05/17] tests: Add test coverage for signals that match the
 message bus's name

This is a special case of unique names, even though it's syntactically
a well-known name.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 161 ++++++++++++++++++++++++++++++++++--
 1 file changed, 154 insertions(+), 7 deletions(-)

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
index 350ec9f52f..af100de7dc 100644
--- a/gio/tests/gdbus-subscribe.c
+++ b/gio/tests/gdbus-subscribe.c
@@ -13,6 +13,7 @@
 #define DBUS_SERVICE_DBUS "org.freedesktop.DBus"
 #define DBUS_PATH_DBUS "/org/freedesktop/DBus"
 #define DBUS_INTERFACE_DBUS DBUS_SERVICE_DBUS
+#define NAME_OWNER_CHANGED "NameOwnerChanged"
 
 /* A signal that each connection emits to indicate that it has finished
  * emitting other signals */
@@ -101,6 +102,7 @@ typedef struct
   const char *iface;
   const char *member;
   const char *arg0;
+  const char *args;
   guint received_by_conn;
   guint received_by_proxy;
 } TestEmitSignal;
@@ -120,6 +122,8 @@ typedef struct
 {
   const char *name;
   TestConn owner;
+  guint received_by_conn;
+  guint received_by_proxy;
 } TestOwnName;
 
 typedef enum
@@ -461,6 +465,63 @@ static const TestPlan plan_limit_by_well_known_name =
   },
 };
 
+static const TestPlan plan_limit_to_message_bus =
+{
+  .description = "A subscription to the message bus only accepts messages "
+                 "from the message bus",
+  .steps = {
+    {
+      /* Subscriber wants to receive signals from the message bus itself */
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .string_sender = DBUS_SERVICE_DBUS,
+        .path = DBUS_PATH_DBUS,
+        .iface = DBUS_INTERFACE_DBUS,
+      },
+    },
+    {
+      /* Attacker wants to trick subscriber into thinking that the message
+       * bus sent a signal */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .path = DBUS_PATH_DBUS,
+        .iface = DBUS_INTERFACE_DBUS,
+        .member = NAME_OWNER_CHANGED,
+        .arg0 = "would I lie to you?",
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* Attacker tries harder, by sending a signal unicast directly to
+       * the subscriber, and using more realistic arguments */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .unicast_to = TEST_CONN_SUBSCRIBER,
+        .sender = TEST_CONN_ATTACKER,
+        .path = DBUS_PATH_DBUS,
+        .iface = DBUS_INTERFACE_DBUS,
+        .member = NAME_OWNER_CHANGED,
+        .args = "('com.example.Name', '', ':1.12')",
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* When the message bus sends a signal (in this case triggered by
+       * owning a name), it should still get through */
+      .action = TEST_ACTION_OWN_NAME,
+      .u.own_name = {
+        .name = OWNED_LATER_NAME,
+        .owner = TEST_CONN_SERVICE,
+        .received_by_conn = 1,
+        .received_by_proxy = 1
+      },
+    },
+  },
+};
+
 typedef struct
 {
   const TestPlan *plan;
@@ -591,7 +652,18 @@ fixture_received_signal (Fixture    *f,
         }
     }
 
-  g_assert_cmpint (received->sender, !=, TEST_CONN_NONE);
+  if (g_str_equal (sender_name, DBUS_SERVICE_DBUS))
+    {
+      g_test_message ("Signal received from message bus %s",
+                      sender_name);
+    }
+  else
+    {
+      g_test_message ("Signal received from %s %s",
+                      test_conn_descriptions[received->sender],
+                      sender_name);
+      g_assert_cmpint (received->sender, !=, TEST_CONN_NONE);
+    }
 
   g_test_message ("Signal received from %s %s via %s",
                   test_conn_descriptions[received->sender],
@@ -607,13 +679,56 @@ fixture_received_signal (Fixture    *f,
       g_test_message ("\tString argument 0: %s", received->arg0);
       g_test_message ("\tSent in step: %u", received->step);
     }
-  else
+  else if (g_variant_is_of_type (parameters, G_VARIANT_TYPE ("(uu)")))
     {
-      g_assert_cmpstr (g_variant_get_type_string (parameters), ==, "(uu)");
       g_variant_get (parameters, "(uu)", NULL, &received->step);
       g_test_message ("\tArgument 0: (not a string)");
       g_test_message ("\tSent in step: %u", received->step);
     }
+  else if (g_variant_is_of_type (parameters, G_VARIANT_TYPE ("(sss)")))
+    {
+      const char *name;
+      const char *old_owner;
+      const char *new_owner;
+
+      /* The only signal of this signature that we legitimately receive
+       * during this test is NameOwnerChanged, so just assert that it
+       * is from the message bus and can be matched to a plausible step.
+       * (This is less thorough than the above, and will not work if we
+       * add a test scenario where a name's ownership is repeatedly
+       * changed while watching NameOwnerChanged - so don't do that.) */
+      g_assert_cmpstr (sender_name, ==, DBUS_SERVICE_DBUS);
+      g_assert_cmpstr (path, ==, DBUS_PATH_DBUS);
+      g_assert_cmpstr (iface, ==, DBUS_INTERFACE_DBUS);
+      g_assert_cmpstr (member, ==, NAME_OWNER_CHANGED);
+
+      g_variant_get (parameters, "(&s&s&s)", &name, &old_owner, &new_owner);
+
+      for (i = 0; i < G_N_ELEMENTS (f->plan->steps); i++)
+        {
+          const TestStep *step = &f->plan->steps[i];
+
+          if (step->action == TEST_ACTION_OWN_NAME)
+            {
+              const TestOwnName *own_name = &step->u.own_name;
+
+              if (g_str_equal (name, own_name->name)
+                  && g_str_equal (new_owner, f->unique_names[own_name->owner])
+                  && own_name->received_by_conn > 0)
+                {
+                  received->step = i;
+                  break;
+                }
+            }
+
+          if (i >= G_N_ELEMENTS (f->plan->steps))
+            g_error ("Could not match message to a test step");
+        }
+    }
+  else
+    {
+      g_error ("Unexpected message received");
+    }
 
   g_ptr_array_add (f->received, g_steal_pointer (&received));
 }
@@ -782,10 +897,15 @@ fixture_emit_signal (Fixture              *f,
    * Otherwise put something that will not match any arg0.
    * Either way, put the sequence number in argument 1 so we can
    * correlate sent messages with received messages later. */
-  if (signal->arg0 != NULL)
+  if (signal->args != NULL)
     {
-      g_test_message ("\tString argument 0: %s", signal->arg0);
       /* floating */
+      body = g_variant_new_parsed (signal->args);
+      g_assert_nonnull (body);
+    }
+  else if (signal->arg0 != NULL)
+    {
+      g_test_message ("\tString argument 0: %s", signal->arg0);
       body = g_variant_new ("(su)", signal->arg0, (guint32) step_number);
     }
   else
@@ -933,8 +1053,6 @@ fixture_run_plan (Fixture          *f,
 
       g_assert_cmpuint (received->step, <, G_N_ELEMENTS (f->received_by_conn));
       g_assert_cmpuint (received->step, <, G_N_ELEMENTS (f->received_by_proxy));
-      g_assert_cmpint (plan->steps[received->step].action,
-                       ==, TEST_ACTION_EMIT_SIGNAL);
 
       if (received->received_by_proxy != NULL)
         f->received_by_proxy[received->step] += 1;
@@ -974,6 +1092,34 @@ fixture_run_plan (Fixture          *f,
               g_assert_cmpuint (f->received_by_proxy[i], ==, 0);
             }
         }
+      else if (step->action == TEST_ACTION_OWN_NAME)
+        {
+          const TestOwnName *own_name = &plan->steps[i].u.own_name;
+
+          if (mode != SUBSCRIPTION_MODE_PROXY)
+            {
+              g_test_message ("NameOwnerChanged from step %u was received %u "
+                              "times by GDBusConnection, expected %u",
+                              i, f->received_by_conn[i], own_name->received_by_conn);
+              g_assert_cmpuint (f->received_by_conn[i], ==, own_name->received_by_conn);
+            }
+          else
+            {
+              g_assert_cmpuint (f->received_by_conn[i], ==, 0);
+            }
+
+          if (mode != SUBSCRIPTION_MODE_CONN)
+            {
+              g_test_message ("NameOwnerChanged from step %u was received %u "
+                              "times by GDBusProxy, expected %u",
+                              i, f->received_by_proxy[i], own_name->received_by_proxy);
+              g_assert_cmpuint (f->received_by_proxy[i], ==, own_name->received_by_proxy);
+            }
+          else
+            {
+              g_assert_cmpuint (f->received_by_proxy[i], ==, 0);
+            }
+        }
     }
 }
 
@@ -1100,6 +1246,7 @@ main (int   argc,
   ADD_SUBSCRIBE_TEST (limit_by_unique_name);
   ADD_SUBSCRIBE_TEST (nonexistent_unique_name);
   ADD_SUBSCRIBE_TEST (limit_by_well_known_name);
+  ADD_SUBSCRIBE_TEST (limit_to_message_bus);
 
   return g_test_run();
 }
-- 
GitLab


From d7240bbd3bb2ce73afd4916b2766f23f09bb6327 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Thu, 14 Mar 2024 19:18:15 +0000
Subject: [PATCH 06/17] gdbusprivate: Add symbolic constants for the message
 bus itself

Using these is a bit more clearly correct than repeating them everywhere.
To avoid excessive diffstat in a branch for a bug fix, I'm not
immediately replacing all existing occurrences of the same literals with
these names.

The names of these constants are chosen to be consistent with libdbus,
despite using somewhat outdated terminology (D-Bus now uses the term
"well-known bus name" for what used to be called a service name,
reserving the word "service" to mean specifically the programs that
have .service files and participate in service activation).

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusprivate.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gio/gdbusprivate.h b/gio/gdbusprivate.h
index e7a5bfa4f1..57147e1729 100644
--- a/gio/gdbusprivate.h
+++ b/gio/gdbusprivate.h
@@ -27,6 +27,11 @@
 
 G_BEGIN_DECLS
 
+/* Bus name, interface and object path of the message bus itself */
+#define DBUS_SERVICE_DBUS "org.freedesktop.DBus"
+#define DBUS_INTERFACE_DBUS DBUS_SERVICE_DBUS
+#define DBUS_PATH_DBUS "/org/freedesktop/DBus"
+
 /* ---------------------------------------------------------------------------------------------------- */
 
 typedef struct GDBusWorker GDBusWorker;
-- 
GitLab


From 0c6fac45269c3df866e409b04b8edeeaf2f9f820 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Thu, 14 Mar 2024 19:24:24 +0000
Subject: [PATCH 07/17] gdbusconnection: Move SignalData, SignalSubscriber
 higher up

Subsequent changes will need to access these data structures from
on_worker_message_received(). No functional change here, only moving
code around.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 128 +++++++++++++++++++++---------------------
 1 file changed, 65 insertions(+), 63 deletions(-)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 1ee2ab44f3..f6fca24b1d 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -284,6 +284,71 @@ call_destroy_notify (GMainContext  *context,
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+typedef struct
+{
+  /* All fields are immutable after construction. */
+  gatomicrefcount ref_count;
+  GDBusSignalCallback callback;
+  gpointer user_data;
+  GDestroyNotify user_data_free_func;
+  guint id;
+  GMainContext *context;
+} SignalSubscriber;
+
+static SignalSubscriber *
+signal_subscriber_ref (SignalSubscriber *subscriber)
+{
+  g_atomic_ref_count_inc (&subscriber->ref_count);
+  return subscriber;
+}
+
+static void
+signal_subscriber_unref (SignalSubscriber *subscriber)
+{
+  if (g_atomic_ref_count_dec (&subscriber->ref_count))
+    {
+      /* Destroy the user data. It doesn’t matter which thread
+       * signal_subscriber_unref() is called in (or whether it’s called with a
+       * lock held), as call_destroy_notify() always defers to the next
+       * #GMainContext iteration. */
+      call_destroy_notify (subscriber->context,
+                           subscriber->user_data_free_func,
+                           subscriber->user_data);
+
+      g_main_context_unref (subscriber->context);
+      g_free (subscriber);
+    }
+}
+
+typedef struct
+{
+  gchar *rule;
+  gchar *sender;
+  gchar *sender_unique_name; /* if sender is unique or org.freedesktop.DBus, then that name... otherwise blank */
+  gchar *interface_name;
+  gchar *member;
+  gchar *object_path;
+  gchar *arg0;
+  GDBusSignalFlags flags;
+  GPtrArray *subscribers;  /* (owned) (element-type SignalSubscriber) */
+} SignalData;
+
+static void
+signal_data_free (SignalData *signal_data)
+{
+  g_free (signal_data->rule);
+  g_free (signal_data->sender);
+  g_free (signal_data->sender_unique_name);
+  g_free (signal_data->interface_name);
+  g_free (signal_data->member);
+  g_free (signal_data->object_path);
+  g_free (signal_data->arg0);
+  g_ptr_array_unref (signal_data->subscribers);
+  g_free (signal_data);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
 #ifdef G_OS_WIN32
 #define CONNECTION_ENSURE_LOCK(obj) do { ; } while (FALSE)
 #else
@@ -3251,69 +3316,6 @@ g_dbus_connection_remove_filter (GDBusConnection *connection,
 
 /* ---------------------------------------------------------------------------------------------------- */
 
-typedef struct
-{
-  gchar *rule;
-  gchar *sender;
-  gchar *sender_unique_name; /* if sender is unique or org.freedesktop.DBus, then that name... otherwise blank */
-  gchar *interface_name;
-  gchar *member;
-  gchar *object_path;
-  gchar *arg0;
-  GDBusSignalFlags flags;
-  GPtrArray *subscribers;  /* (owned) (element-type SignalSubscriber) */
-} SignalData;
-
-static void
-signal_data_free (SignalData *signal_data)
-{
-  g_free (signal_data->rule);
-  g_free (signal_data->sender);
-  g_free (signal_data->sender_unique_name);
-  g_free (signal_data->interface_name);
-  g_free (signal_data->member);
-  g_free (signal_data->object_path);
-  g_free (signal_data->arg0);
-  g_ptr_array_unref (signal_data->subscribers);
-  g_free (signal_data);
-}
-
-typedef struct
-{
-  /* All fields are immutable after construction. */
-  gatomicrefcount ref_count;
-  GDBusSignalCallback callback;
-  gpointer user_data;
-  GDestroyNotify user_data_free_func;
-  guint id;
-  GMainContext *context;
-} SignalSubscriber;
-
-static SignalSubscriber *
-signal_subscriber_ref (SignalSubscriber *subscriber)
-{
-  g_atomic_ref_count_inc (&subscriber->ref_count);
-  return subscriber;
-}
-
-static void
-signal_subscriber_unref (SignalSubscriber *subscriber)
-{
-  if (g_atomic_ref_count_dec (&subscriber->ref_count))
-    {
-      /* Destroy the user data. It doesn’t matter which thread
-       * signal_subscriber_unref() is called in (or whether it’s called with a
-       * lock held), as call_destroy_notify() always defers to the next
-       * #GMainContext iteration. */
-      call_destroy_notify (subscriber->context,
-                           subscriber->user_data_free_func,
-                           subscriber->user_data);
-
-      g_main_context_unref (subscriber->context);
-      g_free (subscriber);
-    }
-}
-
 static gchar *
 args_to_rule (const gchar      *sender,
               const gchar      *interface_name,
-- 
GitLab


From 735bf2cc81a1b60f9dd1d8507d5eb4c3cb49b78b Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Thu, 14 Mar 2024 19:30:12 +0000
Subject: [PATCH 08/17] gdbusconnection: Factor out signal_data_new_take()

No functional changes, except that the implicit ownership-transfer
for the rule field becomes explicit (the local variable is set to NULL
afterwards).

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 42 ++++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index f6fca24b1d..7cc14785be 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -333,6 +333,30 @@ typedef struct
   GPtrArray *subscribers;  /* (owned) (element-type SignalSubscriber) */
 } SignalData;
 
+static SignalData *
+signal_data_new_take (gchar *rule,
+                      gchar *sender,
+                      gchar *sender_unique_name,
+                      gchar *interface_name,
+                      gchar *member,
+                      gchar *object_path,
+                      gchar *arg0,
+                      GDBusSignalFlags flags)
+{
+  SignalData *signal_data = g_new0 (SignalData, 1);
+
+  signal_data->rule = rule;
+  signal_data->sender = sender;
+  signal_data->sender_unique_name = sender_unique_name;
+  signal_data->interface_name = interface_name;
+  signal_data->member = member;
+  signal_data->object_path = object_path;
+  signal_data->arg0 = arg0;
+  signal_data->flags = flags;
+  signal_data->subscribers = g_ptr_array_new_with_free_func ((GDestroyNotify) signal_subscriber_unref);
+  return g_steal_pointer (&signal_data);
+}
+
 static void
 signal_data_free (SignalData *signal_data)
 {
@@ -3582,16 +3606,14 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
       goto out;
     }
 
-  signal_data = g_new0 (SignalData, 1);
-  signal_data->rule                  = rule;
-  signal_data->sender                = g_strdup (sender);
-  signal_data->sender_unique_name    = g_strdup (sender_unique_name);
-  signal_data->interface_name        = g_strdup (interface_name);
-  signal_data->member                = g_strdup (member);
-  signal_data->object_path           = g_strdup (object_path);
-  signal_data->arg0                  = g_strdup (arg0);
-  signal_data->flags                 = flags;
-  signal_data->subscribers           = g_ptr_array_new_with_free_func ((GDestroyNotify) signal_subscriber_unref);
+  signal_data = signal_data_new_take (g_steal_pointer (&rule),
+                                      g_strdup (sender),
+                                      g_strdup (sender_unique_name),
+                                      g_strdup (interface_name),
+                                      g_strdup (member),
+                                      g_strdup (object_path),
+                                      g_strdup (arg0),
+                                      flags);
   g_ptr_array_add (signal_data->subscribers, subscriber);
 
   g_hash_table_insert (connection->map_rule_to_signal_data,
-- 
GitLab


From 0bd037d154eeb537a927cb89c41eb9022ee20264 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Tue, 23 Apr 2024 20:31:57 +0100
Subject: [PATCH 09/17] gdbusconnection: Factor out add_signal_data()

No functional changes.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 64 +++++++++++++++++++++++++------------------
 1 file changed, 37 insertions(+), 27 deletions(-)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 7cc14785be..e412273f76 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -3460,6 +3460,42 @@ is_signal_data_for_name_lost_or_acquired (SignalData *signal_data)
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+/* called in any thread, connection lock is held */
+static void
+add_signal_data (GDBusConnection *connection,
+                 SignalData      *signal_data)
+{
+  GPtrArray *signal_data_array;
+
+  g_hash_table_insert (connection->map_rule_to_signal_data,
+                       signal_data->rule,
+                       signal_data);
+
+  /* Add the match rule to the bus...
+   *
+   * Avoid adding match rules for NameLost and NameAcquired messages - the bus will
+   * always send such messages to us.
+   */
+  if (connection->flags & G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION)
+    {
+      if (!is_signal_data_for_name_lost_or_acquired (signal_data))
+        add_match_rule (connection, signal_data->rule);
+    }
+
+  signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array,
+                                           signal_data->sender_unique_name);
+  if (signal_data_array == NULL)
+    {
+      signal_data_array = g_ptr_array_new ();
+      g_hash_table_insert (connection->map_sender_unique_name_to_signal_data_array,
+                           g_strdup (signal_data->sender_unique_name),
+                           signal_data_array);
+    }
+  g_ptr_array_add (signal_data_array, signal_data);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
 /**
  * g_dbus_connection_signal_subscribe:
  * @connection: a #GDBusConnection
@@ -3549,7 +3585,6 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
   gchar *rule;
   SignalData *signal_data;
   SignalSubscriber *subscriber;
-  GPtrArray *signal_data_array;
   const gchar *sender_unique_name;
 
   /* Right now we abort if AddMatch() fails since it can only fail with the bus being in
@@ -3615,32 +3650,7 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
                                       g_strdup (arg0),
                                       flags);
   g_ptr_array_add (signal_data->subscribers, subscriber);
-
-  g_hash_table_insert (connection->map_rule_to_signal_data,
-                       signal_data->rule,
-                       signal_data);
-
-  /* Add the match rule to the bus...
-   *
-   * Avoid adding match rules for NameLost and NameAcquired messages - the bus will
-   * always send such messages to us.
-   */
-  if (connection->flags & G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION)
-    {
-      if (!is_signal_data_for_name_lost_or_acquired (signal_data))
-        add_match_rule (connection, signal_data->rule);
-    }
-
-  signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array,
-                                           signal_data->sender_unique_name);
-  if (signal_data_array == NULL)
-    {
-      signal_data_array = g_ptr_array_new ();
-      g_hash_table_insert (connection->map_sender_unique_name_to_signal_data_array,
-                           g_strdup (signal_data->sender_unique_name),
-                           signal_data_array);
-    }
-  g_ptr_array_add (signal_data_array, signal_data);
+  add_signal_data (connection, signal_data);
 
  out:
   g_hash_table_insert (connection->map_id_to_signal_data,
-- 
GitLab


From e4504a03efa359d0b7d34e44f15ecd2fb4dc4c38 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Thu, 14 Mar 2024 19:51:59 +0000
Subject: [PATCH 10/17] gdbusconnection: Factor out
 remove_signal_data_if_unused

No functional change, just removing some nesting. The check for whether
signal_data->subscribers is empty changes from a conditional that tests
whether it is into an early-return if it isn't.

A subsequent commit will add additional conditions that make us consider
a SignalData to be still in use and therefore not eligible to be removed.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 83 +++++++++++++++++++++++++------------------
 1 file changed, 48 insertions(+), 35 deletions(-)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index e412273f76..742b3e8783 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -3664,6 +3664,52 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+/*
+ * Called in any thread.
+ * Must hold the connection lock when calling this, unless
+ * connection->finalizing is TRUE.
+ * May free signal_data, so do not dereference it after this.
+ */
+static void
+remove_signal_data_if_unused (GDBusConnection *connection,
+                              SignalData *signal_data)
+{
+  GPtrArray *signal_data_array;
+
+  if (signal_data->subscribers->len != 0)
+    return;
+
+  g_warn_if_fail (g_hash_table_remove (connection->map_rule_to_signal_data, signal_data->rule));
+
+  signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array,
+                                           signal_data->sender_unique_name);
+  g_warn_if_fail (signal_data_array != NULL);
+  g_warn_if_fail (g_ptr_array_remove (signal_data_array, signal_data));
+
+  if (signal_data_array->len == 0)
+    {
+      g_warn_if_fail (g_hash_table_remove (connection->map_sender_unique_name_to_signal_data_array,
+                                           signal_data->sender_unique_name));
+    }
+
+  /* remove the match rule from the bus unless NameLost or NameAcquired (see subscribe()) */
+  if ((connection->flags & G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION) &&
+      !is_signal_data_for_name_lost_or_acquired (signal_data) &&
+      !g_dbus_connection_is_closed (connection) &&
+      !connection->finalizing)
+    {
+      /* The check for g_dbus_connection_is_closed() means that
+       * sending the RemoveMatch message can't fail with
+       * G_IO_ERROR_CLOSED, because we're holding the lock,
+       * so on_worker_closed() can't happen between the check we just
+       * did, and releasing the lock later.
+       */
+      remove_match_rule (connection, signal_data->rule);
+    }
+
+  signal_data_free (signal_data);
+}
+
 /* called in any thread */
 /* must hold lock when calling this (except if connection->finalizing is TRUE)
  * returns the number of removed subscribers */
@@ -3672,7 +3718,6 @@ unsubscribe_id_internal (GDBusConnection *connection,
                          guint            subscription_id)
 {
   SignalData *signal_data;
-  GPtrArray *signal_data_array;
   guint n;
   guint n_removed = 0;
 
@@ -3699,40 +3744,8 @@ unsubscribe_id_internal (GDBusConnection *connection,
                                            GUINT_TO_POINTER (subscription_id)));
       n_removed++;
       g_ptr_array_remove_index_fast (signal_data->subscribers, n);
-
-      if (signal_data->subscribers->len == 0)
-        {
-          g_warn_if_fail (g_hash_table_remove (connection->map_rule_to_signal_data, signal_data->rule));
-
-          signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array,
-                                                   signal_data->sender_unique_name);
-          g_warn_if_fail (signal_data_array != NULL);
-          g_warn_if_fail (g_ptr_array_remove (signal_data_array, signal_data));
-
-          if (signal_data_array->len == 0)
-            {
-              g_warn_if_fail (g_hash_table_remove (connection->map_sender_unique_name_to_signal_data_array,
-                                                   signal_data->sender_unique_name));
-            }
-
-          /* remove the match rule from the bus unless NameLost or NameAcquired (see subscribe()) */
-          if ((connection->flags & G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION) &&
-              !is_signal_data_for_name_lost_or_acquired (signal_data) &&
-              !g_dbus_connection_is_closed (connection) &&
-              !connection->finalizing)
-            {
-              /* The check for g_dbus_connection_is_closed() means that
-               * sending the RemoveMatch message can't fail with
-               * G_IO_ERROR_CLOSED, because we're holding the lock,
-               * so on_worker_closed() can't happen between the check we just
-               * did, and releasing the lock later.
-               */
-              remove_match_rule (connection, signal_data->rule);
-            }
-
-          signal_data_free (signal_data);
-        }
-
+      /* May free signal_data */
+      remove_signal_data_if_unused (connection, signal_data);
       goto out;
     }
 
-- 
GitLab


From 1446111327a210688dd7ddcfe76a3ea484caedd7 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Tue, 23 Apr 2024 20:39:05 +0100
Subject: [PATCH 11/17] gdbusconnection: Stop storing sender_unique_name in
 SignalData

This will become confusing when we start tracking the owner of a
well-known-name sender, and it's redundant anyway. Instead, track the
1 bit of data that we actually need: whether it's a well-known name.

Strictly speaking this too is redundant, because it's syntactically
derivable from the sender, but only via extra string operations.
A subsequent commit will add a data structure to keep track of the
owner of a well-known-name sender, at which point this boolean will
be replaced by the presence or absence of that data structure.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 742b3e8783..805ef1870c 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -324,19 +324,19 @@ typedef struct
 {
   gchar *rule;
   gchar *sender;
-  gchar *sender_unique_name; /* if sender is unique or org.freedesktop.DBus, then that name... otherwise blank */
   gchar *interface_name;
   gchar *member;
   gchar *object_path;
   gchar *arg0;
   GDBusSignalFlags flags;
   GPtrArray *subscribers;  /* (owned) (element-type SignalSubscriber) */
+  gboolean sender_is_its_own_owner;
 } SignalData;
 
 static SignalData *
 signal_data_new_take (gchar *rule,
                       gchar *sender,
-                      gchar *sender_unique_name,
+                      gboolean sender_is_its_own_owner,
                       gchar *interface_name,
                       gchar *member,
                       gchar *object_path,
@@ -347,7 +347,7 @@ signal_data_new_take (gchar *rule,
 
   signal_data->rule = rule;
   signal_data->sender = sender;
-  signal_data->sender_unique_name = sender_unique_name;
+  signal_data->sender_is_its_own_owner = sender_is_its_own_owner;
   signal_data->interface_name = interface_name;
   signal_data->member = member;
   signal_data->object_path = object_path;
@@ -362,7 +362,6 @@ signal_data_free (SignalData *signal_data)
 {
   g_free (signal_data->rule);
   g_free (signal_data->sender);
-  g_free (signal_data->sender_unique_name);
   g_free (signal_data->interface_name);
   g_free (signal_data->member);
   g_free (signal_data->object_path);
@@ -3451,7 +3450,7 @@ remove_match_rule (GDBusConnection *connection,
 static gboolean
 is_signal_data_for_name_lost_or_acquired (SignalData *signal_data)
 {
-  return g_strcmp0 (signal_data->sender_unique_name, "org.freedesktop.DBus") == 0 &&
+  return g_strcmp0 (signal_data->sender, "org.freedesktop.DBus") == 0 &&
          g_strcmp0 (signal_data->interface_name, "org.freedesktop.DBus") == 0 &&
          g_strcmp0 (signal_data->object_path, "/org/freedesktop/DBus") == 0 &&
          (g_strcmp0 (signal_data->member, "NameLost") == 0 ||
@@ -3463,7 +3462,8 @@ is_signal_data_for_name_lost_or_acquired (SignalData *signal_data)
 /* called in any thread, connection lock is held */
 static void
 add_signal_data (GDBusConnection *connection,
-                 SignalData      *signal_data)
+                 SignalData      *signal_data,
+                 const char      *sender_unique_name)
 {
   GPtrArray *signal_data_array;
 
@@ -3483,12 +3483,12 @@ add_signal_data (GDBusConnection *connection,
     }
 
   signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array,
-                                           signal_data->sender_unique_name);
+                                           sender_unique_name);
   if (signal_data_array == NULL)
     {
       signal_data_array = g_ptr_array_new ();
       g_hash_table_insert (connection->map_sender_unique_name_to_signal_data_array,
-                           g_strdup (signal_data->sender_unique_name),
+                           g_strdup (sender_unique_name),
                            signal_data_array);
     }
   g_ptr_array_add (signal_data_array, signal_data);
@@ -3585,6 +3585,7 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
   gchar *rule;
   SignalData *signal_data;
   SignalSubscriber *subscriber;
+  gboolean sender_is_its_own_owner;
   const gchar *sender_unique_name;
 
   /* Right now we abort if AddMatch() fails since it can only fail with the bus being in
@@ -3620,6 +3621,11 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
   rule = args_to_rule (sender, interface_name, member, object_path, arg0, flags);
 
   if (sender != NULL && (g_dbus_is_unique_name (sender) || g_strcmp0 (sender, "org.freedesktop.DBus") == 0))
+    sender_is_its_own_owner = TRUE;
+  else
+    sender_is_its_own_owner = FALSE;
+
+  if (sender_is_its_own_owner)
     sender_unique_name = sender;
   else
     sender_unique_name = "";
@@ -3643,14 +3649,14 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
 
   signal_data = signal_data_new_take (g_steal_pointer (&rule),
                                       g_strdup (sender),
-                                      g_strdup (sender_unique_name),
+                                      sender_is_its_own_owner,
                                       g_strdup (interface_name),
                                       g_strdup (member),
                                       g_strdup (object_path),
                                       g_strdup (arg0),
                                       flags);
   g_ptr_array_add (signal_data->subscribers, subscriber);
-  add_signal_data (connection, signal_data);
+  add_signal_data (connection, signal_data, sender_unique_name);
 
  out:
   g_hash_table_insert (connection->map_id_to_signal_data,
@@ -3674,22 +3680,28 @@ static void
 remove_signal_data_if_unused (GDBusConnection *connection,
                               SignalData *signal_data)
 {
+  const gchar *sender_unique_name;
   GPtrArray *signal_data_array;
 
   if (signal_data->subscribers->len != 0)
     return;
 
+  if (signal_data->sender_is_its_own_owner)
+    sender_unique_name = signal_data->sender;
+  else
+    sender_unique_name = "";
+
   g_warn_if_fail (g_hash_table_remove (connection->map_rule_to_signal_data, signal_data->rule));
 
   signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array,
-                                           signal_data->sender_unique_name);
+                                           sender_unique_name);
   g_warn_if_fail (signal_data_array != NULL);
   g_warn_if_fail (g_ptr_array_remove (signal_data_array, signal_data));
 
   if (signal_data_array->len == 0)
     {
       g_warn_if_fail (g_hash_table_remove (connection->map_sender_unique_name_to_signal_data_array,
-                                           signal_data->sender_unique_name));
+                                           sender_unique_name));
     }
 
   /* remove the match rule from the bus unless NameLost or NameAcquired (see subscribe()) */
-- 
GitLab


From 56aa0a2d05d92b39f4bd4150cca4441487af24f2 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Tue, 23 Apr 2024 20:42:17 +0100
Subject: [PATCH 12/17] gdbus: Track name owners for signal subscriptions

We will use this in a subsequent commit to prevent signals from an
impostor from being delivered to a subscriber.

To avoid message reordering leading to misleading situations, this does
not use the existing mechanism for watching bus name ownership, which
delivers the ownership changes to other main-contexts. Instead, it all
happens on the single thread used by the GDBusWorker, so the order in
which messages are received is the order in which they are processed.

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 350 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 343 insertions(+), 7 deletions(-)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 805ef1870c..0a5f9b691c 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -321,6 +321,31 @@ signal_subscriber_unref (SignalSubscriber *subscriber)
 }
 
 typedef struct
+{
+  /*
+   * 1 reference while waiting for GetNameOwner() to finish
+   * 1 reference for each SignalData that points to this one as its
+   *   shared_name_watcher
+   */
+  grefcount ref_count;
+
+  gchar *owner;
+  guint32 get_name_owner_serial;
+} WatchedName;
+
+static WatchedName *
+watched_name_new (void)
+{
+  WatchedName *watched_name = g_new0 (WatchedName, 1);
+
+  g_ref_count_init (&watched_name->ref_count);
+  watched_name->owner = NULL;
+  return g_steal_pointer (&watched_name);
+}
+
+typedef struct SignalData SignalData;
+
+struct SignalData
 {
   gchar *rule;
   gchar *sender;
@@ -330,13 +355,36 @@ typedef struct
   gchar *arg0;
   GDBusSignalFlags flags;
   GPtrArray *subscribers;  /* (owned) (element-type SignalSubscriber) */
-  gboolean sender_is_its_own_owner;
-} SignalData;
+
+  /*
+   * If the sender is a well-known name, this is an unowned SignalData
+   * representing the NameOwnerChanged signal that tracks its owner.
+   * NULL if sender is NULL.
+   * NULL if sender is its own owner (a unique name or DBUS_SERVICE_DBUS).
+   *
+   * Invariants: if not NULL, then
+   * shared_name_watcher->sender == DBUS_SERVICE_DBUS
+   * shared_name_watcher->interface_name == DBUS_INTERFACE_DBUS
+   * shared_name_watcher->member == "NameOwnerChanged"
+   * shared_name_watcher->object_path == DBUS_PATH_DBUS
+   * shared_name_watcher->arg0 == sender
+   * shared_name_watcher->flags == NONE
+   * shared_name_watcher->watched_name == NULL
+   */
+  SignalData *shared_name_watcher;
+
+  /*
+   * Non-NULL if this SignalData is another SignalData's shared_name_watcher.
+   * One reference for each SignalData that has this one as its
+   * shared_name_watcher.
+   * Otherwise NULL.
+   */
+  WatchedName *watched_name;
+};
 
 static SignalData *
 signal_data_new_take (gchar *rule,
                       gchar *sender,
-                      gboolean sender_is_its_own_owner,
                       gchar *interface_name,
                       gchar *member,
                       gchar *object_path,
@@ -347,7 +395,6 @@ signal_data_new_take (gchar *rule,
 
   signal_data->rule = rule;
   signal_data->sender = sender;
-  signal_data->sender_is_its_own_owner = sender_is_its_own_owner;
   signal_data->interface_name = interface_name;
   signal_data->member = member;
   signal_data->object_path = object_path;
@@ -360,6 +407,17 @@ signal_data_new_take (gchar *rule,
 static void
 signal_data_free (SignalData *signal_data)
 {
+  /* The SignalData should not be freed while it still has subscribers */
+  g_assert (signal_data->subscribers->len == 0);
+
+  /* The SignalData should not be freed while it is watching for
+   * NameOwnerChanged on behalf of another SignalData */
+  g_assert (signal_data->watched_name == NULL);
+
+  /* The SignalData should be detached from its name watcher, if any,
+   * before it is freed */
+  g_assert (signal_data->shared_name_watcher == NULL);
+
   g_free (signal_data->rule);
   g_free (signal_data->sender);
   g_free (signal_data->interface_name);
@@ -367,6 +425,7 @@ signal_data_free (SignalData *signal_data)
   g_free (signal_data->object_path);
   g_free (signal_data->arg0);
   g_ptr_array_unref (signal_data->subscribers);
+
   g_free (signal_data);
 }
 
@@ -498,6 +557,7 @@ struct _GDBusConnection
 
   /* Map used for managing method replies, protected by @lock */
   GHashTable *map_method_serial_to_task;  /* guint32 -> owned GTask* */
+  GHashTable *map_method_serial_to_name_watcher;  /* guint32 -> unowned SignalData* */
 
   /* Maps used for managing signal subscription, protected by @lock */
   GHashTable *map_rule_to_signal_data;                      /* match rule (gchar*)    -> SignalData */
@@ -746,6 +806,7 @@ g_dbus_connection_finalize (GObject *object)
     g_error_free (connection->initialization_error);
 
   g_hash_table_unref (connection->map_method_serial_to_task);
+  g_hash_table_unref (connection->map_method_serial_to_name_watcher);
 
   g_hash_table_unref (connection->map_rule_to_signal_data);
   g_hash_table_unref (connection->map_id_to_signal_data);
@@ -1150,6 +1211,7 @@ g_dbus_connection_init (GDBusConnection *connection)
   g_mutex_init (&connection->init_lock);
 
   connection->map_method_serial_to_task = g_hash_table_new_full (g_direct_hash, g_direct_equal, NULL, g_object_unref);
+  connection->map_method_serial_to_name_watcher = g_hash_table_new_full (g_direct_hash, g_direct_equal, NULL, NULL);
 
   connection->map_rule_to_signal_data = g_hash_table_new (g_str_hash,
                                                           g_str_equal);
@@ -2277,6 +2339,191 @@ g_dbus_connection_send_message_with_reply_sync (GDBusConnection        *connecti
 
 /* ---------------------------------------------------------------------------------------------------- */
 
+/*
+ * Called in any thread.
+ * Must hold the connection lock when calling this, unless
+ * connection->finalizing is TRUE.
+ */
+static void
+name_watcher_unref_watched_name (GDBusConnection *connection,
+                                 SignalData *name_watcher)
+{
+  WatchedName *watched_name = name_watcher->watched_name;
+
+  g_assert (watched_name != NULL);
+
+  if (!g_ref_count_dec (&watched_name->ref_count))
+    return;
+
+  /* Removing watched_name from the name_watcher may result in
+   * name_watcher being freed, so we must make sure name_watcher is no
+   * longer in map_method_serial_to_name_watcher.
+   *
+   * If we stop watching the name while our GetNameOwner call was still
+   * in-flight, then when the reply eventually arrives, we will not find
+   * its serial number in the map and harmlessly ignore it as a result. */
+  if (watched_name->get_name_owner_serial != 0)
+    g_hash_table_remove (connection->map_method_serial_to_name_watcher,
+                         GUINT_TO_POINTER (watched_name->get_name_owner_serial));
+
+  name_watcher->watched_name = NULL;
+  g_free (watched_name->owner);
+  g_free (watched_name);
+}
+
+/* called in GDBusWorker thread with lock held */
+static void
+name_watcher_set_name_owner_unlocked (SignalData *name_watcher,
+                                      const char *new_owner)
+{
+  if (new_owner != NULL && new_owner[0] == '\0')
+    new_owner = NULL;
+
+  g_assert (name_watcher->watched_name != NULL);
+  g_set_str (&name_watcher->watched_name->owner, new_owner);
+}
+
+/* called in GDBusWorker thread with lock held */
+static void
+name_watcher_deliver_name_owner_changed_unlocked (SignalData *name_watcher,
+                                                  GDBusMessage *message)
+{
+  GVariant *body;
+
+  body = g_dbus_message_get_body (message);
+
+  if (G_LIKELY (body != NULL && g_variant_is_of_type (body, G_VARIANT_TYPE ("(sss)"))))
+    {
+      const char *name;
+      const char *new_owner;
+
+      g_variant_get (body, "(&s&s&s)", &name, NULL, &new_owner);
+
+      /* Our caller already checked this */
+      g_assert (g_strcmp0 (name_watcher->arg0, name) == 0);
+
+      if (G_LIKELY (new_owner[0] == '\0' || g_dbus_is_unique_name (new_owner)))
+        name_watcher_set_name_owner_unlocked (name_watcher, new_owner);
+      else
+        g_warning ("Received NameOwnerChanged signal with invalid owner \"%s\" for \"%s\"",
+                   new_owner, name);
+    }
+  else
+    {
+      g_warning ("Received NameOwnerChanged signal with unexpected "
+                 "signature %s",
+                 body == NULL ? "()" : g_variant_get_type_string (body));
+
+    }
+}
+
+/* called in GDBusWorker thread with lock held */
+static void
+name_watcher_deliver_get_name_owner_reply_unlocked (SignalData *name_watcher,
+                                                    GDBusConnection *connection,
+                                                    GDBusMessage *message)
+{
+  GDBusMessageType type;
+  GVariant *body;
+  WatchedName *watched_name;
+
+  watched_name = name_watcher->watched_name;
+  g_assert (watched_name != NULL);
+  g_assert (watched_name->get_name_owner_serial != 0);
+
+  type = g_dbus_message_get_message_type (message);
+  body = g_dbus_message_get_body (message);
+
+  if (type == G_DBUS_MESSAGE_TYPE_ERROR)
+    {
+      if (g_strcmp0 (g_dbus_message_get_error_name (message),
+                     "org.freedesktop.DBus.Error.NameHasNoOwner"))
+        name_watcher_set_name_owner_unlocked (name_watcher, NULL);
+      /* else it's something like NoReply or AccessDenied, which tells
+       * us nothing - leave the owner set to whatever we most recently
+       * learned from NameOwnerChanged, or NULL */
+    }
+  else if (type != G_DBUS_MESSAGE_TYPE_METHOD_RETURN)
+    {
+      g_warning ("Received GetNameOwner reply with unexpected type %d",
+                 type);
+    }
+  else if (G_LIKELY (body != NULL && g_variant_is_of_type (body, G_VARIANT_TYPE ("(s)"))))
+    {
+      const char *new_owner;
+
+      g_variant_get (body, "(&s)", &new_owner);
+
+      if (G_LIKELY (g_dbus_is_unique_name (new_owner)))
+        name_watcher_set_name_owner_unlocked (name_watcher, new_owner);
+      else
+        g_warning ("Received GetNameOwner reply with invalid owner \"%s\" for \"%s\"",
+                   new_owner, name_watcher->arg0);
+    }
+  else
+    {
+      g_warning ("Received GetNameOwner reply with unexpected signature %s",
+                 body == NULL ? "()" : g_variant_get_type_string (body));
+    }
+
+  g_hash_table_remove (connection->map_method_serial_to_name_watcher,
+                       GUINT_TO_POINTER (watched_name->get_name_owner_serial));
+  watched_name->get_name_owner_serial = 0;
+}
+
+/* Called in a user thread, lock is held */
+static void
+name_watcher_call_get_name_owner_unlocked (GDBusConnection *connection,
+                                           SignalData *name_watcher)
+{
+  GDBusMessage *message;
+  GError *local_error = NULL;
+  WatchedName *watched_name;
+
+  g_assert (g_strcmp0 (name_watcher->sender, DBUS_SERVICE_DBUS) == 0);
+  g_assert (g_strcmp0 (name_watcher->interface_name, DBUS_INTERFACE_DBUS) == 0);
+  g_assert (g_strcmp0 (name_watcher->member, "NameOwnerChanged") == 0);
+  g_assert (g_strcmp0 (name_watcher->object_path, DBUS_PATH_DBUS) == 0);
+  /* arg0 of the NameOwnerChanged message is the well-known name whose owner
+   * we are interested in */
+  g_assert (g_dbus_is_name (name_watcher->arg0));
+  g_assert (name_watcher->flags == G_DBUS_SIGNAL_FLAGS_NONE);
+
+  watched_name = name_watcher->watched_name;
+  g_assert (watched_name != NULL);
+  g_assert (watched_name->owner == NULL);
+  g_assert (watched_name->get_name_owner_serial == 0);
+  g_assert (name_watcher->shared_name_watcher == NULL);
+
+  message = g_dbus_message_new_method_call (DBUS_SERVICE_DBUS,
+                                            DBUS_PATH_DBUS,
+                                            DBUS_INTERFACE_DBUS,
+                                            "GetNameOwner");
+  g_dbus_message_set_body (message, g_variant_new ("(s)", name_watcher->arg0));
+
+  if (g_dbus_connection_send_message_unlocked (connection, message,
+                                               G_DBUS_SEND_MESSAGE_FLAGS_NONE,
+                                               &watched_name->get_name_owner_serial,
+                                               &local_error))
+    {
+      g_assert (watched_name->get_name_owner_serial != 0);
+      g_hash_table_insert (connection->map_method_serial_to_name_watcher,
+                           GUINT_TO_POINTER (watched_name->get_name_owner_serial),
+                           name_watcher);
+    }
+  else
+    {
+      g_critical ("Error while sending GetNameOwner() message: %s",
+                  local_error->message);
+      g_clear_error (&local_error);
+      g_assert (watched_name->get_name_owner_serial == 0);
+    }
+
+  g_object_unref (message);
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
 typedef struct
 {
   guint                       id;
@@ -2400,6 +2647,7 @@ on_worker_message_received (GDBusWorker  *worker,
         {
           guint32 reply_serial;
           GTask *task;
+          SignalData *name_watcher;
 
           reply_serial = g_dbus_message_get_reply_serial (message);
           CONNECTION_LOCK (connection);
@@ -2415,6 +2663,19 @@ on_worker_message_received (GDBusWorker  *worker,
             {
               //g_debug ("message reply/error for serial %d but no SendMessageData found for %p", reply_serial, connection);
             }
+
+          name_watcher = g_hash_table_lookup (connection->map_method_serial_to_name_watcher,
+                                              GUINT_TO_POINTER (reply_serial));
+
+          if (name_watcher != NULL)
+            {
+              g_assert (name_watcher->watched_name != NULL);
+              g_assert (name_watcher->watched_name->get_name_owner_serial == reply_serial);
+              name_watcher_deliver_get_name_owner_reply_unlocked (name_watcher,
+                                                                  connection,
+                                                                  message);
+            }
+
           CONNECTION_UNLOCK (connection);
         }
       else if (message_type == G_DBUS_MESSAGE_TYPE_SIGNAL)
@@ -3584,6 +3845,7 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
 {
   gchar *rule;
   SignalData *signal_data;
+  SignalData *name_watcher = NULL;
   SignalSubscriber *subscriber;
   gboolean sender_is_its_own_owner;
   const gchar *sender_unique_name;
@@ -3649,13 +3911,59 @@ g_dbus_connection_signal_subscribe (GDBusConnection     *connection,
 
   signal_data = signal_data_new_take (g_steal_pointer (&rule),
                                       g_strdup (sender),
-                                      sender_is_its_own_owner,
                                       g_strdup (interface_name),
                                       g_strdup (member),
                                       g_strdup (object_path),
                                       g_strdup (arg0),
                                       flags);
   g_ptr_array_add (signal_data->subscribers, subscriber);
+
+  /* If subscribing to a signal from a specific sender with a well-known
+   * name, we must first subscribe to NameOwnerChanged signals for that
+   * well-known name, so that we can match the current owner of the name
+   * against the sender of each signal. */
+  if (sender != NULL && !sender_is_its_own_owner)
+    {
+      gchar *name_owner_rule = NULL;
+
+      /* We already checked that sender != NULL implies MESSAGE_BUS_CONNECTION */
+      g_assert (connection->flags & G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION);
+
+      name_owner_rule = args_to_rule (DBUS_SERVICE_DBUS,
+                                      DBUS_INTERFACE_DBUS,
+                                      "NameOwnerChanged",
+                                      DBUS_PATH_DBUS,
+                                      sender,
+                                      G_DBUS_SIGNAL_FLAGS_NONE);
+      name_watcher = g_hash_table_lookup (connection->map_rule_to_signal_data, name_owner_rule);
+
+      if (name_watcher == NULL)
+        {
+          name_watcher = signal_data_new_take (g_steal_pointer (&name_owner_rule),
+                                               g_strdup (DBUS_SERVICE_DBUS),
+                                               g_strdup (DBUS_INTERFACE_DBUS),
+                                               g_strdup ("NameOwnerChanged"),
+                                               g_strdup (DBUS_PATH_DBUS),
+                                               g_strdup (sender),
+                                               G_DBUS_SIGNAL_FLAGS_NONE);
+          add_signal_data (connection, name_watcher, DBUS_SERVICE_DBUS);
+        }
+
+      if (name_watcher->watched_name == NULL)
+        {
+          name_watcher->watched_name = watched_name_new ();
+          name_watcher_call_get_name_owner_unlocked (connection, name_watcher);
+        }
+      else
+        {
+          g_ref_count_inc (&name_watcher->watched_name->ref_count);
+        }
+
+      signal_data->shared_name_watcher = name_watcher;
+
+      g_clear_pointer (&name_owner_rule, g_free);
+    }
+
   add_signal_data (connection, signal_data, sender_unique_name);
 
  out:
@@ -3683,10 +3991,18 @@ remove_signal_data_if_unused (GDBusConnection *connection,
   const gchar *sender_unique_name;
   GPtrArray *signal_data_array;
 
+  /* Cannot remove while there are still subscribers */
   if (signal_data->subscribers->len != 0)
     return;
 
-  if (signal_data->sender_is_its_own_owner)
+  /* Cannot remove while another SignalData is still using this one
+   * as its shared_name_watcher, which holds watched_name->ref_count > 0 */
+  if (signal_data->watched_name != NULL)
+    return;
+
+  /* Point of no return: we have committed to removing it */
+
+  if (signal_data->sender != NULL && signal_data->shared_name_watcher == NULL)
     sender_unique_name = signal_data->sender;
   else
     sender_unique_name = "";
@@ -3719,6 +4035,15 @@ remove_signal_data_if_unused (GDBusConnection *connection,
       remove_match_rule (connection, signal_data->rule);
     }
 
+  if (signal_data->shared_name_watcher != NULL)
+    {
+      SignalData *name_watcher = g_steal_pointer (&signal_data->shared_name_watcher);
+
+      name_watcher_unref_watched_name (connection, name_watcher);
+      /* May free signal_data */
+      remove_signal_data_if_unused (connection, name_watcher);
+    }
+
   signal_data_free (signal_data);
 }
 
@@ -3991,6 +4316,17 @@ schedule_callbacks (GDBusConnection *connection,
             continue;
         }
 
+      if (signal_data->watched_name != NULL)
+        {
+          /* Invariant: SignalData should only have a watched_name if it
+           * represents the NameOwnerChanged signal */
+          g_assert (g_strcmp0 (sender, DBUS_SERVICE_DBUS) == 0);
+          g_assert (g_strcmp0 (interface, DBUS_INTERFACE_DBUS) == 0);
+          g_assert (g_strcmp0 (path, DBUS_PATH_DBUS) == 0);
+          g_assert (g_strcmp0 (member, "NameOwnerChanged") == 0);
+          name_watcher_deliver_name_owner_changed_unlocked (signal_data, message);
+        }
+
       for (m = 0; m < signal_data->subscribers->len; m++)
         {
           SignalSubscriber *subscriber = signal_data->subscribers->pdata[m];
@@ -4062,7 +4398,7 @@ distribute_signals (GDBusConnection *connection,
         schedule_callbacks (connection, signal_data_array, message, sender);
     }
 
-  /* collect subscribers not matching on sender */
+  /* collect subscribers not matching on sender, or matching a well-known name */
   signal_data_array = g_hash_table_lookup (connection->map_sender_unique_name_to_signal_data_array, "");
   if (signal_data_array != NULL)
     schedule_callbacks (connection, signal_data_array, message, sender);
-- 
GitLab


From 0f2259218572be725beb5ed37623fe48ffd6896b Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Thu, 14 Mar 2024 20:42:41 +0000
Subject: [PATCH 13/17] gdbusconnection: Don't deliver signals if the sender
 doesn't match

Otherwise a malicious connection on a shared bus, especially the system
bus, could trick GDBus clients into processing signals sent by the
malicious connection as though they had come from the real owner of a
well-known service name.

Resolves: https://gitlab.gnome.org/GNOME/glib/-/issues/3268
Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/gdbusconnection.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index 0a5f9b691c..782caff0aa 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -4297,6 +4297,46 @@ schedule_callbacks (GDBusConnection *connection,
       if (signal_data->object_path != NULL && g_strcmp0 (signal_data->object_path, path) != 0)
         continue;
 
+      if (signal_data->shared_name_watcher != NULL)
+        {
+          /* We want signals from a specified well-known name, which means
+           * the signal's sender needs to be the unique name that currently
+           * owns that well-known name, and we will have found this
+           * SignalData in
+           * connection->map_sender_unique_name_to_signal_data_array[""]. */
+          const WatchedName *watched_name;
+          const char *current_owner;
+
+          g_assert (signal_data->sender != NULL);
+          /* Invariant: We never need to watch for the owner of a unique
+           * name, or for the owner of DBUS_SERVICE_DBUS, either of which
+           * is always its own owner */
+          g_assert (!g_dbus_is_unique_name (signal_data->sender));
+          g_assert (g_strcmp0 (signal_data->sender, DBUS_SERVICE_DBUS) != 0);
+
+          watched_name = signal_data->shared_name_watcher->watched_name;
+          g_assert (watched_name != NULL);
+          current_owner = watched_name->owner;
+
+          /* Skip the signal if the actual sender is not known to own
+           * the required name */
+          if (current_owner == NULL || g_strcmp0 (current_owner, sender) != 0)
+            continue;
+        }
+      else if (signal_data->sender != NULL)
+        {
+          /* We want signals from a unique name or o.fd.DBus... */
+          g_assert (g_dbus_is_unique_name (signal_data->sender)
+                    || g_str_equal (signal_data->sender, DBUS_SERVICE_DBUS));
+
+          /* ... which means we must have found this SignalData in
+           * connection->map_sender_unique_name_to_signal_data_array[signal_data->sender],
+           * therefore we would only have found it if the signal's
+           * actual sender matches the required signal_data->sender */
+          g_assert (g_strcmp0 (signal_data->sender, sender) == 0);
+        }
+      /* else the sender is unspecified and we will accept anything */
+
       if (signal_data->arg0 != NULL)
         {
           if (arg0 == NULL)
-- 
GitLab


From 8104afb4f47d9b1b76e34393b189da44b747017c Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Fri, 8 Mar 2024 19:51:50 +0000
Subject: [PATCH 14/17] tests: Add a test for matching by two well-known names

The expected result is that because TEST_CONN_SERVICE owns
ALREADY_OWNED_NAME but not (yet) OWNED_LATER_NAME, the signal will be
delivered to the subscriber for the former but not the latter.
Before #3268 was fixed, it was incorrectly delivered to both.

Reproduces: https://gitlab.gnome.org/GNOME/glib/-/issues/3268 (partially)
Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
index af100de7dc..171d6107d9 100644
--- a/gio/tests/gdbus-subscribe.c
+++ b/gio/tests/gdbus-subscribe.c
@@ -440,6 +440,19 @@ static const TestPlan plan_limit_by_well_known_name =
         .iface = EXAMPLE_INTERFACE,
       },
     },
+    {
+      /* When the service sends a signal with the name it already owns,
+       * it should get through */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 1,
+        .received_by_proxy = 1
+      },
+    },
     {
       /* Service claims another name */
       .action = TEST_ACTION_OWN_NAME,
-- 
GitLab


From 92e4c83d1722b790b63fa0f15909619bbb78e161 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Fri, 8 Mar 2024 19:53:22 +0000
Subject: [PATCH 15/17] tests: Add a test for signal filtering by well-known
 name

The vulnerability reported as GNOME/glib#3268 can be characterized
as: these signals from an attacker should not be delivered to either
the GDBusConnection or the GDBusProxy, but in fact they are (in at
least some scenarios).

Reproduces: https://gitlab.gnome.org/GNOME/glib/-/issues/3268
Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
index 171d6107d9..5406ba7e21 100644
--- a/gio/tests/gdbus-subscribe.c
+++ b/gio/tests/gdbus-subscribe.c
@@ -440,6 +440,33 @@ static const TestPlan plan_limit_by_well_known_name =
         .iface = EXAMPLE_INTERFACE,
       },
     },
+    {
+      /* Attacker wants to trick subscriber into thinking that service
+       * sent a signal */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
+    {
+      /* Attacker tries harder, by sending a signal unicast directly to
+       * the subscriber */
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_ATTACKER,
+        .unicast_to = TEST_CONN_SUBSCRIBER,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        .received_by_proxy = 0
+      },
+    },
     {
       /* When the service sends a signal with the name it already owns,
        * it should get through */
-- 
GitLab


From 8a4afb8396dc0b13a4801d9800f7401567019e66 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@collabora.com>
Date: Tue, 23 Apr 2024 21:39:43 +0100
Subject: [PATCH 16/17] tests: Ensure that unsubscribing with GetNameOwner
 in-flight doesn't crash

This was a bug that existed during development of this branch; make sure
it doesn't come back.

This test fails with a use-after-free and crash if we comment out the
part of name_watcher_unref_watched_name() that removes the name watcher
from `map_method_serial_to_name_watcher`.

It would also fail with an assertion failure if we asserted in
name_watcher_unref_watched_name() that get_name_owner_serial == 0
(i.e. that GetNameOwner is not in-flight at destruction).

Signed-off-by: Simon McVittie <smcv@collabora.com>
---
 gio/tests/gdbus-subscribe.c | 52 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/gio/tests/gdbus-subscribe.c b/gio/tests/gdbus-subscribe.c
index 5406ba7e21..4cba4f5656 100644
--- a/gio/tests/gdbus-subscribe.c
+++ b/gio/tests/gdbus-subscribe.c
@@ -116,6 +116,7 @@ typedef struct
   const char *member;
   const char *arg0;
   GDBusSignalFlags flags;
+  gboolean unsubscribe_immediately;
 } TestSubscribe;
 
 typedef struct
@@ -141,6 +142,7 @@ typedef struct
     TestEmitSignal signal;
     TestSubscribe subscribe;
     TestOwnName own_name;
+    guint unsubscribe_undo_step;
   } u;
 } TestStep;
 
@@ -505,6 +507,43 @@ static const TestPlan plan_limit_by_well_known_name =
   },
 };
 
+static const TestPlan plan_unsubscribe_immediately =
+{
+  .description = "Unsubscribing before GetNameOwner can return doesn't result in a crash",
+  .steps = {
+    {
+      /* Service already owns one name */
+      .action = TEST_ACTION_OWN_NAME,
+      .u.own_name = {
+        .name = ALREADY_OWNED_NAME,
+        .owner = TEST_CONN_SERVICE
+      },
+    },
+    {
+      .action = TEST_ACTION_SUBSCRIBE,
+      .u.subscribe = {
+        .string_sender = ALREADY_OWNED_NAME,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .unsubscribe_immediately = TRUE
+      },
+    },
+    {
+      .action = TEST_ACTION_EMIT_SIGNAL,
+      .u.signal = {
+        .sender = TEST_CONN_SERVICE,
+        .path = EXAMPLE_PATH,
+        .iface = EXAMPLE_INTERFACE,
+        .member = FOO_SIGNAL,
+        .received_by_conn = 0,
+        /* The proxy can't unsubscribe, except by destroying the proxy
+         * completely, which we don't currently implement in this test */
+        .received_by_proxy = 1
+      },
+    },
+  },
+};
+
 static const TestPlan plan_limit_to_message_bus =
 {
   .description = "A subscription to the message bus only accepts messages "
@@ -855,8 +894,18 @@ fixture_subscribe (Fixture             *f,
                                                subscribe->flags,
                                                subscribed_signal_cb,
                                                f, NULL);
+
       g_assert_cmpuint (id, !=, 0);
-      f->subscriptions[step_number] = id;
+
+      if (subscribe->unsubscribe_immediately)
+        {
+          g_test_message ("\tImmediately unsubscribing");
+          g_dbus_connection_signal_unsubscribe (subscriber, id);
+        }
+      else
+        {
+          f->subscriptions[step_number] = id;
+        }
     }
 
   if (f->mode != SUBSCRIPTION_MODE_CONN)
@@ -1287,6 +1336,7 @@ main (int   argc,
   ADD_SUBSCRIBE_TEST (nonexistent_unique_name);
   ADD_SUBSCRIBE_TEST (limit_by_well_known_name);
   ADD_SUBSCRIBE_TEST (limit_to_message_bus);
+  ADD_SUBSCRIBE_TEST (unsubscribe_immediately);
 
   return g_test_run();
 }
-- 
GitLab


From 23367e8445147f42674798e966f6706f2954b472 Mon Sep 17 00:00:00 2001
From: Simon McVittie <smcv@debian.org>
Date: Mon, 6 May 2024 21:24:53 +0100
Subject: [PATCH 17/17] gdbus-proxy test: Wait before asserting name owner has
 gone away

GDBusConnection sends each signal to recipients in a separate idle
callback, and there's no particular guarantee about the order in which
they're scheduled or dispatched. For the NameOwnerChanged signal that
reports the name becoming unowned, it's possible that g_bus_watch_name()
gets its idle callback called before the GDBusProxy:g-name-owner
machinery has updated the name owner, in which case the assertion
will fail.

Fixing GNOME/glib#3268 introduced a new subscription to NameOwnerChanged
which can alter the order of delivery, particularly in the case where
G_DBUS_PROXY_FLAGS_NO_MATCH_RULE was used (as tested in
/gdbus/proxy/no-match-rule). The resulting test failure is intermittent,
but reliably appears within 100 repetitions of that test.

Fixes: 511c5f5b "tests: Wait for gdbus-testserver to die when killing it"
Signed-off-by: Simon McVittie <smcv@debian.org>
---
 gio/tests/gdbus-proxy.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gio/tests/gdbus-proxy.c b/gio/tests/gdbus-proxy.c
index ac5f720fad..ab36eae0e1 100644
--- a/gio/tests/gdbus-proxy.c
+++ b/gio/tests/gdbus-proxy.c
@@ -780,6 +780,12 @@ kill_test_service (GDBusConnection *connection)
   while (!name_disappeared)
     g_main_context_iteration (NULL, TRUE);
 
+  /* GDBusConnection doesn't guarantee that different subscriptions to the
+   * same signal will get their callbacks scheduled in any particular order,
+   * so make sure they have all happened */
+  while (g_main_context_iteration (NULL, FALSE))
+    continue;
+
   g_bus_unwatch_name (watch_id);
 #else
   g_warning ("Can't kill com.example.TestService");
-- 
GitLab

